A test has 6 true/false questions. If you guess the answer to each questions, find the probability...?

A test has 6 true/false questions. If you guess the answer to each questions, find the probability that you get at least 4 correct answers.








A. 13.4%


B. 24.8%


C. 34.4%


D. 56.6%A test has 6 true/false questions. If you guess the answer to each questions, find the probability...?
this is a problem of binomial distribution.





when probabilities of success / failure are equal,


the formula for k successes in n attempts simplifies to


P[k] = nCk / 2^n





so P[%26gt;=4] = P[4] + P[5] + P[6]





= (6C4 + 6C5 + 6C6) / 2^6





= 22 / 64





= 11/32 or 34.375 % ==%26gt; 34.4 %





ans: [ C ]