There are 17 students in a certain class. On the day the te

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?

A. 78
B. 80
C. 87
D. 91
E. 94


I took this question from Magoosh . I saw somebody coming up with a very quick solution -

"When Taqeesha took the test, the average increased from 77 to 78. That means, Taqeesha scored 78 plus 1 mark for each one of the other students. i.e., 78 + 16 = 94."

approach is unclear

I could easily solve this using the conventional way i.e with average formula . I would like to understand the above approach . Also, Kindly help me with some similar questions that I can practice to make sure I nail this concept well .


As always , thank you !