# Averages Quiz Set 011

### Question 1

A box contains 5 marbles each having a weight of 66 grams. The box also contains 25 marbles each having a weight of 96 grams. What is the average weight of all the marbles in the box?

A

91 grams.

B

92 grams.

C

90 grams.

D

89 grams.

Soln.
Ans: a

The weighted average = \${5 × 66 + 25 × 96}/30\$, which equals \${330 + 2400}/30\$ = 91.

### Question 2

The sales(in rupees) of a gift shop for six consecutive days is 5028, 3042, 4446, 786, 5376 and 2838. What is the overall average sale for these six days?

A

Rs.3586.

B

Rs.3592.

C

Rs.3580.

D

Rs.3598.

Soln.
Ans: a

The total sale on first six days is 5028 + 3042 + 4446 + 786 + 5376 + 2838 = 21516. The average for 6 days is: 21516/6, which gives Rs. 3586.

### Question 3

Two of the 28 numbers are 24 and 58, If these two are excluded the average of the remaining 26 numbers is 1 more than the average of all the 28 numbers. What is the average of all the 28 numbers?

A

28.

B

29.

C

27.

D

30.

Soln.
Ans: a

Let the required average be x. Then \$28x - (24 + 58) = 26 × (x - 1).\$ which gives \$28x - 82 = 26 × (x - 1).\$ Solving for x we get x = 28.

### Question 4

If the average of p and q is 20, the average of q and r is 54, and of r and p is 64, then what is the value of p?

A

30.

B

31.

C

29.

D

32.

Soln.
Ans: a

We have three equations (p + q)/2 = average of pq, (q + r)/2 = average of qr and (r + p)/2 = average of rp. Adding these three we get p + q + r = (average of pq + average of qr + average of rp) = (20 + 54 + 64) = 138. So p = 138 - (q + r) = 138 - (2 × average of q and r) = 138 - 2 × 54 = 30.

### Question 5

What is the increase in the average of 11 numbers if the number 13 is replaced by 112?

A

9.

B

10.

C

8.

D

11.

Soln.
Ans: a

If a number r is replaced by a number R, the increase/decrease of average is determined according to the formula \$(R - r)/n\$. So in our case we have R = 112, r = 13, n = 11. So increase = \$(112 - 13)/11\$ = 9.