1. A student multiplies a number X by 5 instead of dividing it by 5. What is the percentage change in the result due to this mistake?

a. 25%

b. 24%

c. 2500%

d. 2400%

## EXPLANATION

Let number is 100

It is multiplied by 5 we get 500

Now actual result should be

100 / 5 = 20

So % change in result

500 – 20 / 20 * 100

2400

2. A retailer buys 40 pens at the marked price of 36 pens from a wholesaler. If he sells these pens giving a discount of 1%, what is the profit percent?

a. 10%

b. 12%

c. 15%

d. 20%

## EXPLANATION

Let marked and sale price be Rs 100/-

Then sale amount= 40*100= 4000

Discount allowed@ 1%=4000*1/100= 40

Sale amount after discount= 4000–40=3960

Cost price of 40 pens which is equavalent of

36 pens= 3600

Profit=net sale amount- cost=3960–3600= 360

Profit Percentage=360/3600*100= 10%

3. How many kilograms of rice costing Rs. 8 per kg must be mixed with 36 kg of rice costing Rs. 5.40 per kg so that 20% gain may be obtained by selling the mixture at Rs. 7.20 per kg?

(kg = kilograms, Rs. = Rupees)

a. 10.8 kg

b. 9.8 kg

c. 11.8 kg

d. 12.8 kg

## EXPLANATION

SP of mixture = Rs 7.20/kg

Therefore, CP = 100/120 * 7.20 = Rs 6/kg

8 : 5.4 = 3 : 10

3 * 3.6 = 10.8 kg

3. Three men rent a farm for Rs. 7000 per annum. ‘A’ puts 110 cows in the farm for 3 months, ‘B’ puts 110 cows for 6 months and ‘C’ puts 440 cows for 3 months. What percentage of the total expenditure should ‘A’ pay? (Rs. = Rupees)

a. 20%

b. 14.28%

c. 16.66%

d. 11.01%

## EXPLANATION

We have to take the ratio of no of cows × months

We get 110×3:110×6: 440×3 =3:6:12 =1:2:4

A should bear 1/7 part = 1×100/7= 14.28%.

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