Average Test-7 (Complete Revision)

Answer: Option A

Explanation

Given,

Average of 100 numbers is 50 = 100×50= 5000

Later, while caluclating average  two numbers namely 71 and 65 were wrongly read as 17 and 56

= 5000+71+65-17-56

= 5063

The correct average is= $\frac{5063}{100}$

= 50.63

Hence, Option A is correct.

Answer: Option C

Explanation

The total marks obtained in 3 subjects A, B, C is 80

= 3×80= 240

The marks obtained by B is more than A and C

B= 40, A= 20, C= 20

The marks obtained by A and C together = A+C

= 20+20

= 40

Hence, Option C is correct.

Answer: Option B

Explanation

Given,

Average marks obtained by 12 students caluclated as 72

= 12×72 = 864

later, it was found that 1 student was wrongly read as 86 instead of 68

= (864-86+68)

= 846

The Correct average = $\frac{846}{12}$

= 70.5

Hence, Option B s correct.

Answer: Option B

Explanation

Given,

Average weight of 5 persons is decreased by 3 kg

= 5×3= 15

later, when one of the man whose wieght is 60 kg replaced by a new man

= 60-x

The weight of the new man is = (Avg weight of 5 persons =difference of new replacement)

⇒ 15 = 60-x

⇒ x = 45kg.

Hence, Option B is correct.

Answer: Option E

Explanation

Given, Average age of 6 persons is 42

The average age of 6 persons is decreased by 1 yr (A= 42-1, N= 6)

= 6×41= 246

when new person included in the group (A=41, N= 6+1)

= 7×41= 287

The age of new man= 287-246

= 41

Hence, Option E is correct.