31
The average weight of boys in a class is 30 kg and the average weight of girls in the same class is 20 kg. If the average weight of the whole class is 23.25 kg, what could be the possible strength of boys and girls respectively in the same class?
A.
B.
C.
D.
Answer & Solution
Solution:
Let, the number of boys and girls in the class
area x and y.
According to given information,
Þ 30x + 20y = 23.25(x +
y)
Þ 30x + 20y = 23.25x +
23.25y
Þ 30x - 23.25x = 23.25y
- 20y
Þ 6.75x = 3.25y
Þ x/y = 3.25/6.75 =
13/27
Hence, possible number of boys and girls 13
and 27 respectively.
32
The average weight of a group of 75 girls was calculated as 47 kgs. It was later discovered that the weight of one of the girls was read as 45 kgs. Whereas her actual weight was 25 kgs. What is the actual average weight of the group of 75 girls?
A.
B.
C.
D.
Answer & Solution
Solution:
Average weight of 75 girls = 47 kg
Total weight of 75 girls = 47 × 75 = 3525 kg
Actual weight of 75 girls = x
Correct weight of 75 girls 3525 - 45 + 25 =
3525 - 20 = 3505 kg
\ Required average weight = x = 3905/75
= 46.73 kg
33
The total marks obtained by a student in Physics, Chemistry and Mathematics together is 120 more than the marks obtained by him in Chemistry. What is the average marks obtained by him in Physics and Mathematics together?
A.
B.
C.
D.
Answer & Solution
Solution: