Selected MCQ

Current Question
Two natural numbers whose sum is 72 cannot be in which ratio ____.
  • A. 1: 2
  • B. 3: 5
  • C. 1 : 3
  • D. 3: 4
Correct Answer: D
Explanation:
3:4 gives a total of 7 parts → 72 is not divisible by 7.
Related Question 1
A number is selected at random from the first 50 natural numbeRs. What is the probability that it is divisible by 3 or 5?
  • A. 21/25
  • B. 17/25
  • C. 4/25
  • D. 8/25
Correct Answer: B
Explanation:
Count the multiples and apply the inclusion-exclusion principle → 34/50 = 17/25.
Related Question 2
If the ratio of two numbers is 5:7 and their sum is 144, the numbers are ____.
  • A. 50 and 94
  • B. 60 and 84
  • C. 70 and 74
  • D. 65 and 79
Correct Answer: B
Explanation:
Total parts = 12 → each = 12 → numbers = 60 and 84.
Related Question 3
If ratio of two numbers is 3:5 and difference is 20, numbers are ____.
  • A. 30 and 50
  • B. 40 and 60
  • C. 20 and 40
  • D. 25 and 45
Correct Answer: A
Explanation:
Difference = 2 parts → 1 part = 10.
Related Question 4
If ratio of two numbers is 7:9 and their sum is 160, numbers are ____.
  • A. 60 and 100
  • B. 70 and 90
  • C. 65 and 95
  • D. 75 and 85
Correct Answer: B
Explanation:
Total parts = 16 → each = 10 → numbers 70, 90.
Related Question 5
The sum of cubes of first 5 natural numbers is ____.
  • A. 100
  • B. 225
  • C. 125
  • D. 150
Correct Answer: B
Explanation:
(n(n+1)/2)² = 225.