Candidates of four schools appear in a mathematics test. The data were as follows:
SchoolNo. of CandidatesAverage ScoreI6075II4880IIINot available55IV4050
If the average score of the candidates of all the four schools is 66, find the number of candidates that appeared from school III.
Let the students from 3rd school be x
Average score
=(60×75)+(80×48)+(55×x)+(50×40)60+48+x+40
66=4500+3840+55x+2000148+x
66(148+x)=10340+55x
9768+66x=10340+55x
11x=572 ; x=52