The average of 5 numbers, arranged in a row, is 309. The average of the first two of these numbers is 431 and the average of the last two of these numbers is 231.5. What is the value of the number at the center of the row?
Answer & explanation
Correct answer: option 4
Sum of 5 numbers = 5 x 309 = 1545
Sum of 1st two numbers = 2 x 431 = 862
Sum of last two numbers = 2 x 231.5 = 463
Center number = 1545 - 862 - 463 = 220