Mathematics
NULL
Medium
Question
A group of boys averages 30 kg. After a 35 kg boy joins, the average rises by 1 kg. How many boys were there originally?
A
4
✓ Official correct answer
B
5
C
6
D
7
Community credibility
Registered members can vote for the answer they believe is correct today and explain why. If the facts change after an election or news event, suggest a new option so others can vote it up.
A
4
No member explanations yet for this option.
B
5
No member explanations yet for this option.
C
6
No member explanations yet for this option.
D
7
No member explanations yet for this option.
Explanation
30n + 35 = 31(n + 1) ⇒ n = 4.