Question
7 children are to be selected from a group of 8 boys and
6 girls. In how many ways will the children with at most 3 girls and at least 4 boys be selected?Solution
Case I: 4 boys and 3 girls can be selected, Number of ways of selection = 8C4 × 6C3 = 70 × 20 = 1400 Case II: 5 boys and 2 girls can be selected, Number of ways of selection = 8C5 × 6C2 = 56 × 15 = 840 Case III: 6 boys and 1 girl can be selected, Number of ways of selection = 8C6 × 6C1 = 28 × 6 = 168 Case IV: 7 boys can be selected, Number of ways of selection = 8C7 = 8 So, total number of ways of selecting the children = 1400 + 840 + 168 + 8 = 2416 ways
Find the area of the triangle whose vertices are (3, 6), (– 3, 2) and (4, 1).
A group of 30 students has an average score of 60 in an exam. If 5 more students join the group and their average score is 70, find the new average scor...
-Constable/1727177343-23.JPG)
A mixture of milk and honey is being sold at the price of pure milk, yielding a 20% profit. If 5 liters of honey is added to this mixture, the milk-to-h...
A person buys 2 items for ₹300 each. He sells one at a profit of 10% and the other at a loss of 10%. What is the overall gain or loss percentage?
If (a + b) = 8 and ab = 10, then find the value of (a2 + b2).
Find the average of the following set of numbers: 13, 42, 22, 35, 68.
A solid sphere is perfectly inscribed inside a cube, and a right circular cylinder is placed inside the cube such that it touches all the faces of the c...
Relevant for Exams:
