The average height of 50 bats is 126cm. Some bats of average height 120cm are removed. If the new average height is 130cm, then how many bats are remaining?
- A12
- B20
- C16
- D30
Solution & Step-by-step Explanation
Let the number of bats removed be x.
Therefore, the number of remaining bats is (50−x).
Total height of 50 bats = 50×126=6300cm
Total height of bats removed = x×120=120x
Total height of remaining bats = (50−x)×130
According to the question:
6300−120x=130(50−x)
6300−120x=6500−130x
130x−120x=6500−6300
10x=200
x=20
Number of bats removed = 20
Remaining bats = 50−20=30
Therefore, the number of remaining bats is (50−x).
Total height of 50 bats = 50×126=6300cm
Total height of bats removed = x×120=120x
Total height of remaining bats = (50−x)×130
According to the question:
6300−120x=130(50−x)
6300−120x=6500−130x
130x−120x=6500−6300
10x=200
x=20
Number of bats removed = 20
Remaining bats = 50−20=30