Scores of 68, 67 and 88 on three of four tests. if his average on all four tests was 73.5, his score on the fourth test was

X= fourth test score

Add the 4 test scores and divide that total by 4 to equal the average.

(68 + 67 + 88 + x)/4= 73.5
add in parentheses

(223 + x)/4= 73.5
multiply both sides by 4

223 + x= 294
subtract 223 from both sides

x= 71

ANSWER: 71 was the score on the 4th test.

Hope this helps! :)