the average weight of 18 students ina class is 15 kg. if one student leaves the class, the average weight decreased by 0.8 kg. what is the weight of that student?
a) 25.5kg
b)26.6kg
c)29.6kg
d)28.6kg
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Hey mate !!
Here's your answer !!
Average weight = Sum of all weights / Total number of people
Average weight = 15
Total number of people = 18
Sum of all weights = ?
= 15 = x / 18
= x = 15 * 18
=> x = 270 kgs
One boy leaves the class so the average weight decreases by 0.8 kg
Average weight = 15 - 0.8 = 14.2
Total number of students = 17 students
The new sum = y
= 14.2 = y / 17
= y = 14.2 * 17
= y = 241.4 kgs
So the old sum - new sum = Boy's weight
= x - y = Boys's weight
= 270 - 241.4 = 28.6 kgs
Hence option (d) is correct.
Hope it helps !!
Cheers !!
Here's your answer !!
Average weight = Sum of all weights / Total number of people
Average weight = 15
Total number of people = 18
Sum of all weights = ?
= 15 = x / 18
= x = 15 * 18
=> x = 270 kgs
One boy leaves the class so the average weight decreases by 0.8 kg
Average weight = 15 - 0.8 = 14.2
Total number of students = 17 students
The new sum = y
= 14.2 = y / 17
= y = 14.2 * 17
= y = 241.4 kgs
So the old sum - new sum = Boy's weight
= x - y = Boys's weight
= 270 - 241.4 = 28.6 kgs
Hence option (d) is correct.
Hope it helps !!
Cheers !!
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