Question
A bag contains 3 blue, 2 green, and 5 black pens. If
five pens are selected randomly, what is the probability that exactly two are green and three are black?Solution
Total number of outcomes = C (n, r) = C (10,5)Â 
= 252 number of favorable outcomes = C (5,3) × C (2,2) = 10 × 1 = 10 ∴ Required probability = 10/252 = 5/126
If x : y : z = 6 : 7 : 11, and (2x + 3z) = 180, then find the value of y.
The sum of two numbers is 45 and their difference is 9. What is the larger number?
If x + y + z = 20, x² + Y² + z² = 160 and x z = y², then find the value of x z?
If (a3+1)/(a+1) = (a3-1)/(a-1) and a ≠1, -1. Find the value of 'a'
If (10 a³ + 4b³): (11a³ — 15b³) = 7:5, then (3a + 5b): (9a - 2b) = ?
If cos(A - B) = √3/2 and cot(A + B) = 1/√3, where A - B and A + B are acute angles, then (2A - 3B) is equal to:
[a/(2a²  + 5a + 2)] = 1/6 , then find the value of (a+1)/a ?
If √e + (1/√e) = 10, then find the value of e + (1/e).
If x – 1/x = 9, then x3 – 1/x3 is:
