Selected MCQ

Current Question
The average of first 10 natural numbers ____.
  • A. 5
  • B. 5.5
  • C. 6
  • D. 6.5
Correct Answer: B
Explanation:
Sum/10.
Related Question 1
The sum of five numbers is 655. The average of the first two is 85. Find the sum of the last three.
  • A. 180
  • B. 170
  • C. 190
  • D. 175
Correct Answer: A
Explanation:
Subtract known sum.
Related Question 2
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 3
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.
Related Question 4
The sum of squares of first 5 natural numbers is ____.
  • A. 50
  • B. 55
  • C. 60
  • D. 65
Correct Answer: B
Explanation:
The formula gives 55.
Related Question 5
From first 20 natural numbers, probability of selecting even number is ____.
  • A. 1/2
  • B. 16/19
  • C. 4/5
  • D. 17/20
Correct Answer: A
Explanation:
10 even numbers → 10/20 = 1/2.