Question

The average of 15 test scores is 80. If the average of first eight test scores is 65 and that of the last eight test scores is 70, then the eighth score is 80.

True or False?

Answer 1

• False

Explanation:

The average of 15 test scores is 80.

The total is:

• 15*80 = 1200

The average of first eight test scores is 65.

The total is:

• 8*65 = 520

The average of last eight test scores is 70.

The total minus 8th score is:

• 8*70 - 80 = 480

The sum gives us the total of 15 scores:

• 520 + 480 = 1000 < 1200

The answer is FALSE