Practice Increase or decrease in interest rate - quantitative aptitude Online Quiz (set-1) For All Competitive Exams
Q-1) A man loses Rs.55.50 yearly when the annual rate of interest falls from 11.5% to 10%. His capital (in rupees) is
(a)
(b)
(c)
(d)
Using Rule 1,
Let his capital be x.
According to the question,
${x × 11.5}/100 - {x × 10}/100$ = 55.50
or (11.5 - 10)x = 5550
or 1.5x = 5550
or $x = 5550/{1.5}$ = Rs.3700
Q-2) A sum of Rs.400 amounts to Rs.480 in 4 years. What will it amount to if the rate of interest is increased by 2%?
(a)
(b)
(c)
(d)
Using Rule 1Simple Interest (S.I.)= ${\text"Principal × Rate × Time"/100$ orS.I. = ${\text"P × R × T"/100$P = ${\text"S.I." × 100}/\text"R × T"$, R = ${\text"S.I." × 100}/\text"P × T"$, T = ${\text"S.I." × 100}/\text"P × R"$ A = P + S.I. or S.I. = A - P
Interest = Rs.(480–400) = Rs.80
80 = ${400 × r × 4}/100$ ⇒ r = 5
Now, r = 7% (2% increase)
S.I. = ${400 × 7 × 4}/100$ = 112
Amount = Rs.(400+112) = Rs.512
Q-3) The amount Rs.2,100 became Rs.2,352 in 2 years at simple interest. If the interest rate is decreased by 1%, what is the new interest ?
(a)
(b)
(c)
(d)
Using Rule 1,
S.I. = 2352 - 2100 = Rs.252
Rate = ${\text"S.I." × 100}/\text" Principal × Time"$
= ${252 × 100}/{2100 × 2}$ = 6% per annum
New rate = 5%
S.I. = ${252 × 5}/6$ = Rs.210
Q-4) If the annual rate of simple interest increases from 10% to 12$1/2$% , a man's yearly income increases by Rs.1250. His principal (in rupees) is
(a)
(b)
(c)
(d)
Using Rule 1,
Change in SI
= $(25/2 - 10)% = 5/2%$
$5/2$% of principal = Rs.1250
Principal = Rs.${1250 × 2 × 100}/5$ = Rs.50000
Q-5) A sum of Rs. 800 amounts to Rs.920 in 3 years at the simple interest rate. If the rate is increased by 3% p.a., what will be the sum amount to in the same period ?
(a)
(b)
(c)
(d)
Using Rule 1,
Case I,
S.I. = 920 - 800 = Rs.120
Rate = ${\text"S.I." × 100}/\text" Principal × Time"$
= ${120 × 100}/{800 × 3}$ = 5% per annum
Case II,
Rate = 8% per annum
S.I. = ${800 × 8 × 3}/100$ = Rs.192
Amount = Principal + S.I.
= (800 + 192) = Rs.992
Q-6) A sum was lent at simple interest at a certain rate for 2 years. Had it been lent at 3% higher rate, it would have fetched Rs.300 more. The original sum of money was :
(a)
(b)
(c)
(d)
If the principal be x, then
${x × 3 × 2}/100 = 300$
$x = {300 × 100}/{3 × 2}$ = Rs.5000
Using Rule 13.
$P_1 = P, R_1 = R, T_1$ = 2.
$P_2 = P, R_2 = R + 3, T_2$ = 2.
S.I.= Rs.300
300 = ${P × (R + 3) × 2 - PR2}/100$
300 = ${6P}/100$ = Rs.5000
Q-7) A sum of money was invested at a certain rate of simple interest for 2 years . Had it been invested at 1% higher rate, it would have fetched Rs.24 more interest. The sum of money is :
(a)
(b)
(c)
(d)
${P × 1 × 2}/100 = 24$
P = $2400/2$ = Rs.1200
Using Rule 13,
$P_1 = P, R_1 = R, T_1$ = 2.
$P_2 = P, R_2 = R + 1, T_2$ = 2
S.I.= Rs. 24
24 = ${P(R +1)2 - PR2}/100$
2400 = 2PR + 2P - 2PR
P = Rs.1200
Q-8) A sum of money was lent at simple interest at a certain rate for 3 years. Had it been lent at 2.5% per annum higher rate, it would have fetched Rs.540 more. The money lent was :
(a)
(b)
(c)
(d)
If the sum lent be Rs. x, then
${x × 2.5 × 3}/100 = 540$
$x = {540 × 100}/{2.5 × 3}$ = Rs.7200
Using Rule 13,
$P_1 = P, R_1 = R, T_1$ = 3
$P_2 = P, R_2 = R + 2.5%, T_2$ = 3
S.I. = Rs.540
540 = ${P × (R + 2.5%) × 3 - P × R × 3}/100$
54000 = 7.5P
P = $540000/75$
P = Rs.7200
Q-9) A sum of Rs. 800 becomes Rs. 956 in 3 years at a certain rate of simple interest. If the rate of interest is increased by 4%, what amount will the same sum become in 3 years ?
(a)
(b)
(c)
(d)
Using Rule 1,
S.I. = 956 - 800 = Rs. 156
Rate = ${\text"S.I." × 100}/\text" Principal × Time"$
= ${156 × 100}/{800 × 3}$ = 6.5%
New rate = (6.5 + 4)% = 10.5%
S.I. = ${\text"Principal × Time × Rate"/100$
= ${800 × 3 × 10.5}/100$ = Rs. 252
Amount = Rs.(800 + 252) = Rs.1052
Q-10) The rate of simple interest per annum of bank being decreased from 5% to 3$1/2$%, the annual income of a person from interest was less by Rs. 105. The sum deposited at the bank was
(a)
(b)
(c)
(d)
Using Rule 1,
Amount deposited in bank = Rs.x (let)
Difference of rates
= 5 - $7/2 = 3/2%$ per annum
S.I. = ${\text"Principal × Time × Rate"/100$
${x × 1 × 3}/{100 × 2}$ = 105
$x = {105 × 200}/3$ = Rs.7000