Question Number 133696 by Mikael_786 last updated on 23/Feb/21
![A test consists of four questions each of which contains five alternative answers, one of which is correct. The test pass condition is at least four correct answers. A student, not knowing the test subject, scored the answers randomly.How is the probability for the student to pass?](https://www.tinkutara.com/question/Q133696.png)
$$\mathrm{A}\:\mathrm{test}\:\mathrm{consists}\:\mathrm{of}\:\mathrm{four}\:\mathrm{questions} \\ $$$$\mathrm{each}\:\mathrm{of}\:\mathrm{which}\:\mathrm{contains}\:\mathrm{five}\:\mathrm{alternative} \\ $$$$\mathrm{answers},\:\mathrm{one}\:\mathrm{of}\:\mathrm{which}\:\mathrm{is}\:\mathrm{correct}. \\ $$$$\mathrm{The}\:\mathrm{test}\:\mathrm{pass}\:\mathrm{condition}\:\mathrm{is}\:\mathrm{at}\:\mathrm{least} \\ $$$$\mathrm{four}\:\mathrm{correct}\:\mathrm{answers}.\:\mathrm{A}\:\mathrm{student},\:\mathrm{not} \\ $$$$\mathrm{knowing}\:\mathrm{the}\:\mathrm{test}\:\mathrm{subject},\:\mathrm{scored}\:\mathrm{the} \\ $$$$\mathrm{answers}\:\mathrm{randomly}.\mathrm{How}\:\mathrm{is}\:\mathrm{the} \\ $$$$\mathrm{probability}\:\mathrm{for}\:\mathrm{the}\:\mathrm{student}\:\mathrm{to}\:\mathrm{pass}? \\ $$
Answered by Ar Brandon last updated on 23/Feb/21
![((1/5))^4](https://www.tinkutara.com/question/Q133707.png)
$$\left(\frac{\mathrm{1}}{\mathrm{5}}\right)^{\mathrm{4}} \\ $$