Unit-8:Commercial Mathematics
(a) S.I. and C.I.
(b) Percentage, Profit and Loss, Discount
(c) Time and Work, Time and Distance
Q1.
A sum on compound interest becomes three times in 4 years then with the same interest rate , the sum will become 27 time in ________
years.
(a) 12 (b) 10 (c) 8 (d) 15
Solution.
(x1)1/n1 = (x2)1/n2
(3)1/4 = (27)1/n2
(3)1/4 = (3)3/n2
1/4 = 3/x2
x2 = 12
Solution
Q2.
If the annual rate of simple interest increases from 10% to 12.5% a man's yearly income increases by Rs.1250, then the principal is _________
(a) 35k (b) 40k (c) 65k (d) 50k
Solution.
SI = prt/100
1250 = (p x 2.5 x 1)/100
p = 50,000 = 50k
Solution
Q3.
A sum of money amounts to 6200 in 2 years and amount to 7400 in 3 years, find the sum.
(a) 4500 (b) 5200 (c) 3800
(d) 4000
Solution.
P + 2I = 6200 ----------1
P + 3I = 7400 -----------2
on solving equation 1 and 2,we get
I = 1200
P = 3800
Solution
Q4.
If P% of P is 36 find P.
(a) 80 (b) 60 (c) 50 (d) 40
Solution.
P/100 of P = 36
P2 = 3600
p = 60
Solution
Q5.
Monthly income of a person first increased by 15%,then it is diminished by 5% So, what is the net change in income of the person.
(a) 7% (b) 8.75%
(c) 9.25% (d) 6%
Solution.
= a + b + ab/100
= 15 - 5 - 75/100
= 15 - 5.75
= 9.25%
Solution
Q6.
A trader purchase 6 units in Rs.5 and sells 5 units in Rs.6, find the percentage profit.
(a) 44% (b) 40% (c) 25%
(d) 10%
Solution.
(a) 44%
Solution
Q7.
Discount of 15% on a commodity is equal to the discount of 20% on other commodity. find the values of both commodities.
(a) Rs 85, Rs 60 (b) Rs 80, Rs 60 (c) Rs 60, Rs 40 (d) Rs 40, Rs 20
Solution.
(b) Rs 80, Rs 60
15% of x = 20% of y
(15/100)x = (20/100)y
3x = 4y
x/y = 4/3
x:y = 4:3
Solution
Q8.
A is thrice as fast as B, and is therefore able to finish a work in 60 days less than B. find the time in which they can do it working
together.
(a) 22.5 days (b) 18 days (c) 30.5 days (d) 45 days
Solution.
(a) 22.5 days
Solution
Q9.
Each of the two tables is sold for Rs.720 the first one is sold at 25% profit and the other one at 25% loss. what is the percentage of loss or gain in this deal ?
(a) 7% (b) 6.25% (c) 6% (d) 5.5%
Solution.
In this,there is always loss.
% loss = (25)2/100
= 625/100
= 6.25%
Solution
Q10.
A man travelled a certain distance by train at the rate of 25 km an hour and walked back at the rate of 4 km/hr the whole journey took
5 hrs and 48 minutes. What distance did he travelled ?
(a) 15 km (b) 20 km (c) 10 km (d) 30 km
Solution.
(b) 20 km
Distance =
Total time x
multiplication of two speeds/sum of speeds
Solution
