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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