If the average of 35 numbers is 22, the average of the first 17 numbers is 19, and the average of the last 17 numbers is 20, then the 18th number is:
Answer & explanation
Correct answer: option 2
Sum of 35 number is = 35 × 22 = 770
Sum of first 17 numbers = 17 × 19 = 323
Sum of last 17 numbers = 17 × 20 = 340
18th number = 770 - ( 323 + 340 ) = 770 - 663 = 107