There are 17 students in a certain class. On the day the test was given, Taqeesha was absent. The other 16 students took the test, and their average was 77. The next day, Taqeesha took the test, and with her grade included, the new average is 78. What is Taqeesha’s grade on the test?
78
80
87
91
94
Explanation:
The average of the first 16 students is 77. This means, the sum of these 16 scores is
sum = (average)*(number of scores) = 77*16 = 1232
Once Taqeesha takes her test, the average of all 17 scores is 78. This means, the sum of these 17 scores is:
sum = (average)*(number of scores) =78*17 = 1326
Once we had the sum of the 16 scores, all we had to do was add Taqeesha’s score to that total to get the sum of all 17. Therefore, the difference in these two sums is Taqeesha’s score. 1326 – 1232 = 94.
The average of the first 16 students is 77. This means, the sum of these 16 scores is
sum = (average)*(number of scores) = 77*16 = 1232
Once Taqeesha takes her test, the average of all 17 scores is 78. This means, the sum of these 17 scores is:
sum = (average)*(number of scores) =78*17 = 1326
Once we had the sum of the 16 scores, all we had to do was add Taqeesha’s score to that total to get the sum of all 17. Therefore, the difference in these two sums is Taqeesha’s score. 1326 – 1232 = 94.
