Six tables and twelve chairs were bought for 7,800. If the average price of a table is 750, then the average price of a chair would be
(a) 250
(b) 275
(c) 150
(d) 175
(e) 190
Answer: (b)
Average cost of a chair = ₹ x, then
x × 12 + 6 × 750 = 7800
12x = 7800 – 4500 = 3300
\(\displaystyle x=\frac{{3300}}{{12}}=275\)
The average monthly salary of all the employees in an industry is ₹ 12,000. The average salary of male employees is ₹ 15,000 and that of female employees is ₹ 8,000. What is the ratio of male employees to female employees?
There are 100 students in 3 sections A, B and C of a class. The average marks of all the 3 sections was 84. The average of B and C was 87.5 and the average marks of A is 70. The number of students in A was
(a) 30
(b) 35
(c) 20
(d) 25
(e) 42
Answer: (c)
Number of students in section A = x
Number of students in sections B and C = (100 – x)
\(\displaystyle \Rightarrow \)x × 70 + (100 – x) × 87.5 = 84 × 100
\(\displaystyle \Rightarrow \)70x + 87.5 × 100 – 87.5x = 8400
\(\displaystyle \Rightarrow \)8750 – 17.5x = 8400
\(\displaystyle \Rightarrow \)17.5x = 8750 – 8400 = 350
\(\displaystyle x=\frac{{350}}{{17.5}}=20\)
The average weight of 3 men A, B and C is 84 kg. Another man D joins the group and the average now becomes 80 kg. If another man E whose weight is 3 kg more than that of D, replaces A, then the average weight of B, C, D and E becomes 79 kg. Then weight of A is
(a) 72 kg.
(b) 74 kg.
(c) 75 kg.
(d) 76 kg.
(e) 78 kg.
Answer: (c)
D’s weight = 80 × 4 – 84 × 3 = 320 – 252 = 68 kg.
E’s weight = 68 + 3 = 71 kg.
Total weight of (A + B + C + D + E) = 84 × 3 + 68 + 71
= 252 + 68 + 71 = 391 kg.
Total weight of (B + C + D + E) = 79 × 4 = 316 kg.
A’s weight= 391 – 316 = 75 kg.
A librarian purchased 50 story–books for his library. But he saw that he could get14 more books by spending Rs. 76 more and the average price per book would be reduced by Re. 1. The average price (in Rs.) of each book he bought, was :
(a) 15
(b) 10
(c) 25
(d) 20
(e) 34
Answer: (b)
Let the average cost of each book bought (of 64 books) be x.
According to the question,
64 × x – 50(x + 1) = 76
\(\displaystyle \Rightarrow \)64x – 50x – 50 = 76
\(\displaystyle \Rightarrow \)14x = 76 + 50 = 126
\(\displaystyle x=\frac{{126}}{{14}}=9\)
Required average price= 9 + 1 = 10
