Question 326734
Let Charlie scores N in the fourth test to get an average of 93 marks.
Hence, (88 + 95 + 89 + N)/4 = 93
=> 272 + N = 4 x 93 = 372
=> N = 372 - 272 = 100
Hence, Charlie must score 100 in the fourth test to get an average of 93 marks in all four tests.