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? (Rounded off to two digits after decimal)
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$46.73 kgs.$
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$46.64 kgs.$
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$45.96 kgs.$
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$Can't be determined$
A
Correct answer
Explanation
The recorded total was 75 × 47 = 3525 kg. The actual total should be 3525 - 45 + 25 = 3505 kg (subtracting the wrong reading and adding the correct weight). The actual average is 3505 ÷ 75 = 46.7333... kg, which rounds to 46.73 kg to two decimal places. The error was 20 kg (45 - 25), distributed over 75 girls, so each girl's average was off by 20/75 = 0.2667 kg.