In a class, 5% of the boys and 10% of the girls have an IQ more than 150. In the class 60% of the students are boys and rest girls. If a student is selected at random and found to have an IQ of more than 150, find the probability that the student is a boy.

In Class XI of a school 40 % of the students study Mathematies and 30% study Biology.10% of the class study both mathematics and biology. If a student is selected at random from the class, find the probability that he will be studying Mathemetics or Biology.

In Noorjahan's class 30% of the students are girls. There are 60 students in the class. Let's calculate to find the number of boys in Noorjahan's class.

Of the students in a college, it is known that 60% reside in hostel and 40% are day scholars (not residing in hostel). Previous year results report that 30% of all students who reside in hostel attain A grade and 20% of day scholars attain A grade in their annual examination. At the end of the year, one student is chosen at random from the college and he has an A grade, what is the probability that the student is a hostlier?

In a class of 10 student, probability of exactly i students passing an examination is directly proportional to i^(2). Then answer the following questions: If a students selected at random is found to have passed the examination, then the probability that he was the only student who has passed the examination is

A class consists of 30 boys and 20 girls of which half the boys, and half the girls have blue eyes. Find the probability that a student chosen at random is a boy or has blue eyes.

The number of students in a class is 60 . The average of the ages of the boy-students is 14.5 years and the average of the ages of the girl-students is 16 years . If the collective average of the total students be 15 years , then find the number of boy-students and the number of girl-students.

In a class of 60 students, 40 opted for NCC, 30 opted for NSS and 20 opted for both NCC and NSS. If one of these students is selected at random, then the probability that the student selected has opted neither for NCC nor for NSS is

In a hostel, 60% of the students read Hindi newspaper, 40% read English newspaper and 20% read both Hindi and English newspapers. A student is selected at random. (a) Find the probability that she reads neither Hindi nor English newspapers. (b) If she reads Hindi newspaper, find the probability that she reads English newspaper (c) If she reads English newspaper, find the probability that she reads Hindi newspaper.

How many times must a man toss a fair coin so that the probability of having at least one head is more than 90%?

Assume that the chances of a patient having a heart attack is 40%. It is also assumed that a meditation and yoga course reduce the risk of heart attack by 30% and prescription of certain drug reduces its chances by 25%. At a time a patient can choose any one of the two options with equal probabilities. It is given that after going through one of the two options the patient selected at random suffers a heart attack. Find the probability that the patient followed a course of meditation and yoga?