quant practice questions

[study_hard]

5. Technological advances in manufacturing radios reduced the
manufacturing cost of parts by 50 per cent and the cost of labour by 60 percent. If labour originally accounted for 3 times as much of the
manufacturing cost as parts and it is assumed that total cost consisted only of labour and parts, what was the per cent decrease in the total cost, resulting from these advances?
(A) 30% (B) 42.5% (C) 55% (D) 57.5% (E) 70%

Hey I solved this one as -
[(M + L) - (0.5M + 0.4L)]/(M+L)
where L = 3M
So I get the answer as 57.5%

What's wrong?

[chestnut.cc]

1. A rectangular airport runway is x feet long and y feet wide. If its
length is to be made 100 feet longer, by how many square feet will its area be increased?
(A) xy + 100y (B) xy + 100 (C) 100 ly (D) 100l (E) 100 y

E... :s

2. The probability of A’s winning a hockey match is 3/2 times the
probability of B’s winning a cricket match. The probability of C’s winning a race is twice the probability of B’s winning the cricket match. What is the
maximum probability of A’s winning the hockey match?
(A) ¼ (B) ½ (C) 2/3 (D)¾ (E) 1

Let B = x... A = 3/2*x... C =2x... B<A<C<1... x <3/2*x<2x <1... Plug in the choices... A = 3/4... B=1/2... C=1... D

3. In a certain city, the number of commuters decreased 15 per cent from June to July and decreased 10 per cent from July to August. By
approximately what per cent would the number of commuters have to
increase from August to September for the number of commuters in
September to be equal to the number of commuters in June?
(A) 80% (B) 77% (C) 75% (D) 31% (E) 24%

Consider the no of commuters in June to be 100... it drops 15% to 85 in July... and drops 10% to about 76 in August... to get back up to 100... an increase of 24 commuters is required... which is about 31%...

4. If the distance required for an automobile to stop varies directly as the square of its speed, what is the distance required for an automobile driven at 60 km/hr to stop if it takes 10 meters to stop the automobile moving at 20 km/hr.
(A) 30m (B) 36m (C) 60m (D) 90m (E) 120m

D

5. Technological advances in manufacturing radios reduced the
manufacturing cost of parts by 50 per cent and the cost of labour by 60 percent. If labour originally accounted for 3 times as much of the
manufacturing cost as parts and it is assumed that total cost consisted only of labour and parts, what was the per cent decrease in the total cost, resulting from these advances?
(A) 30% (B) 42.5% (C) 55% (D) 57.5% (E) 70%

Consider the cost of parts as 10... then the cost of labour is 30... total cost is 40... accio technological advances... cost of parts is now 5... and cost of labour is now 12... total cost is reduced to 17... a reduction of about 57.5%... D

6. Of the following, which is the closest to 1?
(A) 1 + 0.04 (B) (1 – 0.04)2 (C) 1- (0.04)½ (D)0.042 (E) 1- 0.043

B is its ^2
C if its *1/2

7. Of the following, whish is the greatest amount of money that a
person can borrow at an annual interest rate of 6.5 per cent if the loan and interest are to be paid off at the end of one year with the money from a check of Rs. 1,600?
(A) Rs. 2,460 (B) Rs. 1,704 (C) Rs. 1,520 (D) Rs. 1,500
(E) Rs. 1,040

C

8. An 8 gram object is attached to a balance beam at a point 22 cm. from the centre of the beam. If the beam is to remain horizontally balanced how many grams must be attached to the other end of the beam 10 cms away from the centre?
(A) 27.5 (B) 17.6 (C) 3.6 (D) 1.8 (E) 0.06

22*8 = 10*x... x = 17.6... B

9. X can clean the garage in half the time it takes B. If they cleaned it together in 3 hours, how many hours would it take form A to clean the garage all by himself?
(A) 6 (B) 5.5 (C) 5 (D) 4.5 (E) 4

D

[study_hard]

Can't solve this one. Please help

A rainstorm increased the amount of water stored in state reservoirs from 124 billion to 138 billion gallons. If the storm increased the amount of water in the reservoirs to 82% of total capacity, approximately how many billion gallons of water were the reservoir short of total capacity prior to the storm?

[chestnut.cc]

Let x be the total capacity of the reservoir... 0.82x = 138... simplify by taking 0.8 and 140... x = 140/0.8... x = 175 billion gallons... Sans the storm the reservoir lacked 175 - 125 = about 50 billion gallons...

[study_hard]

Originally Posted by chestnut.cc

Let x be the total capacity of the reservoir... 0.82x = 138... simplify by taking 0.8 and 140... x = 140/0.8... x = 175 billion gallons... Sans the storm the reservoir lacked 175 - 125 = about 50 billion gallons...

Thanks buddy, I misinterpreted the questions language.