The average of 4 numbers is 60 and the 1st number is 1/3 off the sum of the remaining three numbers. What is the first number?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 60.
Given:
The average of 4 numbers is 60
The 1st number is 1/3 off the sum of the remaining three numbers
Formula used:
Average = Sum of observations/number of observations ---- (1)
Calculations:
Let the 4 numbers be a, b, c and d
According to the question,
Sum of 4 numbers = a + b + c + d = 4 × 60 = 240 ---- (2)
⇒ a = (1/3) × (b + c + d)
⇒ 3a = b + c + d ---- (3)
Putting the value of equation (3) in equation (2), we get
⇒ a + 3a = 240
⇒ 4a = 240
⇒ a = 60
Hence, the value of first number is 60.