What is the ratio of the average of first eight prime number to the average of first even natural numbers?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 7 : 8
Formula used :
Average = Sum of observation/Number of observations ---- (1)
Calculations :
First eight prime numbers = 2, 3, 5, 7, 11, 13, 17, 19
First ten even natural numbers = 2, 4, 6, 8, 10, 12, 14, 16, 18, 20
Using formula (1)
Average of eight prime numbers
⇒ (2 + 3 + 5 + 7 + 11 + 13 + 17 + 19)/8
⇒ 77/8
Average of first 10 natural even numbers
⇒ (2 + 4 + 6 + 8 + 10 + 12 + 14 + 16 + 18 + 20)/10
⇒ 110/10 = 11
Ratio of the average of first eight prime number to the average of first even natural numbers
⇒ 77/8 : 11
⇒ 7 : 8