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Permutation and CombinationQuestion and Answers: Page 14

Question Number 104134 Answers: 2 Comments: 0

what is the coefficient x^(15) in the expansion of x^6 (1−x)^(11)

$${what}\:{is}\:{the}\:{coefficient}\:{x}^{\mathrm{15}} \\ $$$${in}\:{the}\:{expansion}\:{of}\:{x}^{\mathrm{6}} \left(\mathrm{1}−{x}\right)^{\mathrm{11}} \\ $$

Question Number 103903 Answers: 1 Comments: 5

a 100 cm long rod should be divided into 3 parts. the length of each part in cm should be integer. in how many different ways can this be done?

$${a}\:\mathrm{100}\:{cm}\:{long}\:{rod}\:{should}\:{be}\:{divided} \\ $$$${into}\:\mathrm{3}\:{parts}.\:{the}\:{length}\:{of}\:{each}\:{part} \\ $$$${in}\:{cm}\:{should}\:{be}\:{integer}.\:{in}\:{how}\: \\ $$$${many}\:{different}\:{ways}\:{can}\:{this}\:{be} \\ $$$${done}? \\ $$

Question Number 103826 Answers: 1 Comments: 0

In the expansion of (1+x)^(20) if the coefficient of x^r is twice the coefficient of x^(r−1) , what the value of the coefficient?

$${In}\:{the}\:{expansion}\:{of}\:\left(\mathrm{1}+{x}\right)^{\mathrm{20}} \:{if}\:{the} \\ $$$${coefficient}\:{of}\:{x}^{{r}} \:{is}\:{twice}\:{the}\:{coefficient} \\ $$$${of}\:{x}^{{r}−\mathrm{1}} ,\:{what}\:{the}\:{value}\:{of}\:{the} \\ $$$${coefficient}?\: \\ $$

Question Number 103716 Answers: 1 Comments: 3

Question Number 103606 Answers: 3 Comments: 1

an integer n between 1 and 98 , inclusive is to be chosen at random. what is the probability that n(n+1) will be divisible by 3

$${an}\:{integer}\:{n}\:{between}\:\mathrm{1}\:{and}\:\mathrm{98}\:, \\ $$$${inclusive}\:{is}\:{to}\:{be}\:{chosen}\:{at} \\ $$$${random}.\:{what}\:{is}\:{the}\:{probability} \\ $$$${that}\:{n}\left({n}+\mathrm{1}\right)\:{will}\:{be}\:{divisible}\:{by}\:\mathrm{3} \\ $$

Question Number 103513 Answers: 2 Comments: 0

coefficient of x^5 in expansion (1+x^2 )^5 (1+x)^4 equal to (a) 40 (b) 45 (c) 50 (d) 55 (e) 60

$${coefficient}\:{of}\:{x}^{\mathrm{5}} \:{in}\:{expansion} \\ $$$$\left(\mathrm{1}+{x}^{\mathrm{2}} \right)^{\mathrm{5}} \left(\mathrm{1}+{x}\right)^{\mathrm{4}} \:{equal}\:{to}\: \\ $$$$\left({a}\right)\:\mathrm{40}\:\:\:\:\:\:\left({b}\right)\:\mathrm{45}\:\:\:\:\:\left({c}\right)\:\mathrm{50}\:\:\:\:\left({d}\right)\:\mathrm{55} \\ $$$$\left({e}\right)\:\mathrm{60} \\ $$

Question Number 103410 Answers: 1 Comments: 0

Σ_(k=0) ^n (((−1)^k )/(k!))=?

$$\underset{\mathrm{k}=\mathrm{0}} {\overset{\mathrm{n}} {\sum}}\frac{\left(−\mathrm{1}\right)^{\mathrm{k}} }{\mathrm{k}!}=? \\ $$

Question Number 103406 Answers: 0 Comments: 3

100 students are standing in a row. 4 students should be selected in the way that no two of them are next to each other. how many ways do you have to do this?

$$\mathrm{100}\:{students}\:{are}\:{standing}\:{in}\:{a}\:{row}. \\ $$$$\mathrm{4}\:{students}\:{should}\:{be}\:{selected}\:{in}\:{the} \\ $$$${way}\:{that}\:{no}\:{two}\:{of}\:{them}\:{are}\:{next}\:{to} \\ $$$${each}\:{other}.\:{how}\:{many}\:{ways}\:{do}\:{you} \\ $$$${have}\:{to}\:{do}\:{this}? \\ $$

Question Number 103367 Answers: 1 Comments: 0

many words with 4 letters can be formed using letters from the word TINKUTARA is ___

$${many}\:{words}\:{with}\:\mathrm{4}\:{letters}\:{can}\:{be}\:{formed} \\ $$$${using}\:{letters}\:{from}\:{the}\:{word} \\ $$$${TINKUTARA}\:{is}\:\_\_\_ \\ $$

Question Number 103357 Answers: 1 Comments: 0

There are 21 students will be trained with 6 trainers available. Every students is trained by 1 coach and every coach trains students with different amounts. many ways of grouping students who will be trained are .... (a) ((21!)/(6!)) (b) 6!.21! (c) ((21!)/(2!.3!.4!.5! )) (d) 6×21! (e) ((21!)/(15!))×6!

$${There}\:{are}\:\mathrm{21}\:{students}\:{will}\:{be}\:{trained} \\ $$$${with}\:\mathrm{6}\:{trainers}\:{available}.\:{Every}\:{students} \\ $$$${is}\:{trained}\:{by}\:\mathrm{1}\:{coach}\:{and}\:{every}\:{coach} \\ $$$${trains}\:{students}\:{with}\:{different}\:{amounts}. \\ $$$${many}\:{ways}\:{of}\:{grouping}\:{students}\:{who} \\ $$$${will}\:{be}\:{trained}\:{are}\:.... \\ $$$$\left({a}\right)\:\frac{\mathrm{21}!}{\mathrm{6}!}\:\:\:\:\left({b}\right)\:\mathrm{6}!.\mathrm{21}!\:\:\:\:\:\left({c}\right)\:\frac{\mathrm{21}!}{\mathrm{2}!.\mathrm{3}!.\mathrm{4}!.\mathrm{5}!\:\:}\:\: \\ $$$$\left({d}\right)\:\mathrm{6}×\mathrm{21}!\:\:\:\:\left({e}\right)\:\frac{\mathrm{21}!}{\mathrm{15}!}×\mathrm{6}! \\ $$

Question Number 103300 Answers: 1 Comments: 0

many positive five−digit integers with the first number 1 and there are three equal numbers ? (a) 810 (b) 720 (c)120 (d) 60 (e) 20

$$\mathrm{many}\:\mathrm{positive}\:\mathrm{five}−\mathrm{digit} \\ $$$$\mathrm{integers}\:\mathrm{with}\:\mathrm{the}\:\mathrm{first}\:\mathrm{number}\:\mathrm{1} \\ $$$$\mathrm{and}\:\mathrm{there}\:\mathrm{are}\:\mathrm{three}\:\mathrm{equal} \\ $$$$\mathrm{numbers}\:? \\ $$$$\left(\mathrm{a}\right)\:\mathrm{810}\:\:\:\:\left(\mathrm{b}\right)\:\mathrm{720}\:\:\:\:\left(\mathrm{c}\right)\mathrm{120} \\ $$$$\left(\mathrm{d}\right)\:\mathrm{60}\:\:\:\:\:\left(\mathrm{e}\right)\:\mathrm{20} \\ $$

Question Number 103294 Answers: 1 Comments: 0

from letters in ′MATEMATIKA′ words formed by using all the letters . How many words that can be formed with the five consonant are always side by side

$$\mathrm{from}\:\mathrm{letters}\:\mathrm{in} \\ $$$$'\mathrm{MATEMATIKA}'\:\mathrm{words} \\ $$$$\mathrm{formed}\:\mathrm{by}\:\mathrm{using}\:\mathrm{all}\:\mathrm{the}\:\mathrm{letters}\:. \\ $$$$\mathrm{How}\:\mathrm{many}\:\mathrm{words}\:\mathrm{that}\:\mathrm{can}\:\mathrm{be} \\ $$$$\mathrm{formed}\:\mathrm{with}\:\mathrm{the}\:\mathrm{five}\:\mathrm{consonant} \\ $$$$\mathrm{are}\:\mathrm{always}\:\mathrm{side}\:\mathrm{by}\:\mathrm{side}\: \\ $$

Question Number 102816 Answers: 2 Comments: 28

How many 6 digit numbers exist whose digits have exactly the sum 13? for example 120505 is such a number.

$${How}\:{many}\:\mathrm{6}\:{digit}\:{numbers}\:{exist} \\ $$$${whose}\:{digits}\:{have}\:{exactly}\:{the}\:{sum}\:\mathrm{13}? \\ $$$$ \\ $$$${for}\:{example}\:\mathrm{120505}\:{is}\:{such}\:{a}\:{number}. \\ $$

Question Number 102800 Answers: 1 Comments: 0

There are 14 boys and 10 girls in a classroom. The teacher wants to form a team of 5 students . The team must have a least two boys and two girls . Find the number of ways the team can be chosen.

$$\mathrm{There}\:\mathrm{are}\:\mathrm{14}\:\mathrm{boys}\:\mathrm{and}\:\mathrm{10}\:\mathrm{girls}\:\mathrm{in} \\ $$$$\mathrm{a}\:\mathrm{classroom}.\:\mathrm{The}\:\mathrm{teacher}\:\mathrm{wants} \\ $$$$\mathrm{to}\:\mathrm{form}\:\mathrm{a}\:\mathrm{team}\:\mathrm{of}\:\mathrm{5}\:\mathrm{students}\:. \\ $$$$\mathrm{The}\:\mathrm{team}\:\mathrm{must}\:\mathrm{have}\:\mathrm{a}\:\mathrm{least}\:\mathrm{two} \\ $$$$\mathrm{boys}\:\mathrm{and}\:\mathrm{two}\:\mathrm{girls}\:.\:\mathrm{Find}\:\mathrm{the} \\ $$$$\mathrm{number}\:\mathrm{of}\:\mathrm{ways}\:\mathrm{the}\:\mathrm{team}\:\mathrm{can}\:\mathrm{be} \\ $$$$\mathrm{chosen}.\: \\ $$

Question Number 102329 Answers: 0 Comments: 0

Question Number 101880 Answers: 2 Comments: 0

Find the number of six−digit odd numbers without repeated digits.

$${Find}\:{the}\:{number}\:{of}\:{six}−{digit}\:{odd} \\ $$$${numbers}\:{without}\:{repeated}\:{digits}. \\ $$

Question Number 101732 Answers: 2 Comments: 1

There are 10 identical mathematics books, 7 identical physics books and 5 identical chemistry books. Find the number of ways to compile the books under the condition that same books are not mutually adjacent.

$$\mathrm{There}\:\mathrm{are}\:\mathrm{10}\:\mathrm{identical}\:\mathrm{mathematics} \\ $$$$\mathrm{books},\:\mathrm{7}\:\mathrm{identical}\:\mathrm{physics}\:\mathrm{books} \\ $$$$\mathrm{and}\:\mathrm{5}\:\mathrm{identical}\:\mathrm{chemistry}\:\mathrm{books}. \\ $$$$\mathrm{Find}\:\mathrm{the}\:\mathrm{number}\:\mathrm{of}\:\mathrm{ways}\:\mathrm{to}\:\mathrm{compile}\: \\ $$$$\mathrm{the}\:\mathrm{books}\:\mathrm{under}\:\mathrm{the}\:\mathrm{condition}\:\mathrm{that} \\ $$$$\mathrm{same}\:\mathrm{books}\:\mathrm{are}\:\mathrm{not}\:\mathrm{mutually}\:\mathrm{adjacent}. \\ $$

Question Number 101393 Answers: 1 Comments: 0

Question Number 100971 Answers: 1 Comments: 0

A woman sent 8 letters to her friends. The letters are kept in the addressed envelopes at random. The probability that 4 friends receive correct letters and 4 letters go to wrong destination, is ___

$$\mathrm{A}\:\mathrm{woman}\:\mathrm{sent}\:\mathrm{8}\:\mathrm{letters}\:\mathrm{to}\:\mathrm{her}\: \\ $$$$\mathrm{friends}.\:\mathrm{The}\:\mathrm{letters}\:\mathrm{are}\:\mathrm{kept}\:\mathrm{in}\:\mathrm{the} \\ $$$$\mathrm{addressed}\:\mathrm{envelopes}\:\mathrm{at}\:\mathrm{random}.\: \\ $$$$\mathrm{The}\:\mathrm{probability}\:\mathrm{that}\:\mathrm{4}\:\mathrm{friends}\: \\ $$$$\mathrm{receive}\:\mathrm{correct}\:\mathrm{letters}\:\mathrm{and}\:\mathrm{4}\:\mathrm{letters}\: \\ $$$$\mathrm{go}\:\mathrm{to}\:\mathrm{wrong}\:\mathrm{destination},\:\mathrm{is}\:\_\_\_\: \\ $$

Question Number 100444 Answers: 4 Comments: 0

Find the number of five−digit numbers containing exactly three different digits? Examples: 12312, 12224

$${Find}\:{the}\:{number}\:{of}\:{five}−{digit}\:{numbers} \\ $$$${containing}\:{exactly}\:{three}\:{different} \\ $$$${digits}?\:{Examples}:\:\mathrm{12312},\:\mathrm{12224} \\ $$

Question Number 99985 Answers: 0 Comments: 0

A certain wire has length 4.5 cm and mass 12.3 g, with an electrical resistance of 1.1 mΩ. this wire falls through a horizontal magnetic field with flux density of 0.35 T. As his wire falls its ends slide smoothly between two rails connected by a wire with negligible internal resistance. Calculate the magnitude of the terminal energy resistance, neglecting the resistance of the rails.

$$\mathrm{A}\:\mathrm{certain}\:\mathrm{wire}\:\mathrm{has}\:\mathrm{length}\:\mathrm{4}.\mathrm{5}\:\mathrm{cm}\:\mathrm{and}\:\mathrm{mass}\:\mathrm{12}.\mathrm{3}\:\mathrm{g},\:\:\mathrm{with}\:\mathrm{an} \\ $$$$\mathrm{electrical}\:\mathrm{resistance}\:\mathrm{of}\:\mathrm{1}.\mathrm{1}\:\mathrm{m}\Omega.\:\mathrm{this}\:\mathrm{wire}\:\mathrm{falls}\:\mathrm{through}\:\mathrm{a}\:\mathrm{horizontal} \\ $$$$\mathrm{magnetic}\:\mathrm{field}\:\:\mathrm{with}\:\mathrm{flux}\:\mathrm{density}\:\mathrm{of}\:\mathrm{0}.\mathrm{35}\:\mathrm{T}.\:\mathrm{As}\:\mathrm{his}\:\mathrm{wire}\:\mathrm{falls}\:\mathrm{its}\:\mathrm{ends} \\ $$$$\mathrm{slide}\:\mathrm{smoothly}\:\mathrm{between}\:\mathrm{two}\:\mathrm{rails}\:\mathrm{connected}\:\mathrm{by}\:\mathrm{a}\:\mathrm{wire}\:\mathrm{with}\:\mathrm{negligible} \\ $$$$\mathrm{internal}\:\mathrm{resistance}.\:\mathrm{Calculate}\:\mathrm{the}\:\mathrm{magnitude}\:\mathrm{of}\:\mathrm{the}\:\mathrm{terminal}\:\mathrm{energy} \\ $$$$\mathrm{resistance},\:\mathrm{neglecting}\:\mathrm{the}\:\mathrm{resistance}\:\mathrm{of}\:\mathrm{the}\:\mathrm{rails}. \\ $$

Question Number 99905 Answers: 0 Comments: 5

Question Number 99194 Answers: 1 Comments: 0

Question Number 98405 Answers: 1 Comments: 0

Question Number 98406 Answers: 0 Comments: 0

NB:P(E) means a set of all part of E

$$\boldsymbol{{NB}}:\boldsymbol{\mathcal{P}}\left(\boldsymbol{\mathrm{E}}\right)\:\mathrm{means}\:\mathrm{a}\:\mathrm{set}\:\mathrm{of}\:\mathrm{all}\:\mathrm{part}\:\mathrm{of}\:\boldsymbol{\mathrm{E}} \\ $$

Question Number 98030 Answers: 0 Comments: 1

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