Question

Mean of 100 items is 49. It was discovered that three items which should have been 60, 70, 80 were wrongly read as 40, 20, 50 respectively. The correct mean is ______.

Options

• 48

• 49

• 50

• 60

Answer 1

Mean of 100 items is 49. It was discovered that three items which should have been 60, 70, 80 were wrongly read as 40, 20, 50 respectively. The correct mean is 50.

Explanation:-

Sum of 100 observations

= 100 × 49 = 4900

Correct sum

= 4900 - [40 + 20 + 50 ] + [60 + 70 + 80] = 5000

∴ Correct mean = `5000/100=50`