Probability: A multiple choice examination has 5 questions. Each question has… | JEE Main 2013 | Yukti Vault

Yukti Vault

JEE Main 2013 (Offline)Question 1

A multiple choice examination has $5$ questions. Each question has three alternative answers of which exactly one is correct. The probability that a student will get $4$ or more correct answers just by guessing is :

Probability

$\frac{17}{3^{5}}$$\frac{13}{3^{5}}$$\frac{11}{3^{5}}$✓ Correct answer$\frac{10}{3^{5}}$

Solution

$P=\binom54\frac1{3^4}\cdot\frac23+\frac1{3^5}=\frac{10+1}{3^5}=\frac{11}{3^5}$.

More from Probability

There are four machines and it is known that exactly two of them are faulty. They are tested, one by one, in…
A box contains 2 fifty paise coins, 5 twenty five paise coins and a certain fixed number N (ge2) of ten and…
A computer producing factory has only two plants T_1 and T_2 . Plant T_1 produces 20% and plant T_2 produces…
Four dice are thrown simultaneously and the numbers shown on these dice are recorded in 2times2 matrices.…
If the mean and the variance of binomial variate X are 2 and 1 respectively, then the probability that X…
For a biased die the probabilities for the different faces to turn up are given below: Face: 1,\ 2,\ 3,\ 4,\…
Let M be the maximum value of the product of two positive integers when their sum is 66 . Let the sample…
Let A and B two events such that P (overlineAcup B )=frac16 , P(Acap B)=frac14 and P (bar A )=frac14 , where…