Simple Interest ICSE Class-7th Concise Selina Maths

Simple Interest ICSE Class-7th Concise Selina Maths Solutions Chapter-10 . We provide step by step Solutions of Exercise / lesson-10 Simple Interest for ICSE Class-7 Concise Selina Mathematics . Our Solutions contain all type Questions to develop skill and confidence. Visit official Website CISCE for detail information about ICSE Board Class-7.

Simple Interest ICSE Class-7th Concise Selina Maths Solutions Chapter-10

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Exercise – 10 

Question 1.

Find the S.I. and amount on :
(i) Rs. 150 for 4 years at 5% per year.
(ii) Rs. 350 for 3 years at 8% p.a.
(iii) Rs. 620 for 4 months at 8 p. per rupee per month.
(iv) Rs. 3,380 for 30 months at 4  % p.a.
(v) 600 from July 12 to Dec. 5 at 10% p.a.
(vi) Rs. 850 from 10th March to 3rd August at 2  % p.a.
(vii) Rs. 225 for 3 years 9 months at 16% p.a.
Answer

(i)

P = Rs. 150, R = 5% per year T = 4 years

∴ S.I. = (P.R.T)/100

= (150×5×4)/100

= Rs. 30

and amount = P + S.I.

= Rs. 150 + Rs. 30

= Rs. 180

(ii)

P = Rs. 350, R = 8% p.a. T = 3 (1/2) years = 7/2 years

∴ S.I. = (P.R.T)/100

=(350×8×7)/(100×2)

= Rs. 98

and amount = P + S.I.

= Rs. 350 + Rs. 98

= Rs. 448

(iii)

P = Rs. 620, R = 8 p. per rupee per month = 8% p.m..

T = 4 months

∴ S.I. = (P.R.T)/100

=(620×8×4)/100

= Rs. 19840/100

= Rs. 198.40

and amount = P + S.I.

= Rs. 620 + Rs. 198.40

= Rs. 818.40

(iv)

Principal (P) = Rs. 3380

Rate = 4 (1/2)% p.a. = 9/2%

Period = 30 months = 30/12 years

S.I. = (PRT/100)

=(3380×9×30)/(100×2×12)

= Rs. 1521/4

= Rs. 380.25

Amount = P + S.I.

= Rs. 3380 + 380.25

= Rs. 3760.25

(v)

P = Rs. 600, R = 10% p.a.

T = July 12 to Dec. 5

= (146/365) years = 2/5 years

∴ S.I. = (P.R.T)/100

=(600×10×2)/(100×5)

= Rs. 24

∴ Amount = P + S.I.

= Rs. 600 + Rs. 24

= Rs. 624

(vi)

(vii)

Question 2.

On what sum of money does the S.I. for 10 years at 5% become Rs. 1,600 ?
Answer

S.I. = Rs. 1600, R = 5% p.a. T = 10 years

∴ P = (S.I.×100)/(R×T)

=(1600×100)/(5×10) = Rs. 3200

Question 3.

Find the time in which Rs. 2,000 will amount to Rs. 2,330 at 11% p.a. ?
Answer

Question 4.

In what time will a sum of money double it self at 8% p.a ?
Answer

Let the principal (P) = ₹ 100

∴ Amount (A) = ₹ 100 × 2 = ₹ 200

∴ S.I. = A – P = ₹ 200 – ₹ 100 = ₹ 100

Rate (R) = 8 % p.a.

∴ Time = (S.I.×100)/(P×R)

=(100×100)/(100×8)

=25/2

=12 (1/2) years

Question 5.

In how many years will be ₹870 amount to ₹1,044, the rate of interest being 2 % p.a ?
Answer

Question 6.

Find the rate percent if the S.I. on ₹275 is 2 years is ₹22.
Answer

Principal (P) = ₹ 275, S.I. = ₹ 22

Time = 2 years

∴ Rate = (S.I.×100)/P×T

= (22×100)/(275×2)

= 4 % p.a.

Question 7.

Find the sum which will amount to ₹700 in 5 years at 8% rate p.a.
Answer

Question 8.

What is the rate of interest, if ₹3,750 amounts to ₹4,650 in 4 years ?
Answer

Principal (P) = ₹ 3750

Amount (A) = ₹ 4650

∴ S.I. = A – P = ₹ 4650 – 3750 = ₹ 900

Time (T) = 4 years

∴ Rate = (S.I×100)/P×T

= (900×100)/(3750×4)

= 6 % p.a.

Question 9.

In 4 years, ₹6,000 amount to ₹8,000. In what time will ₹525 amount to ₹700 at the same rate ?
Answer

In first case, principal (P) = ₹ 6000

Amount (A) = ₹ 8000

∴ S.I. = A – P = ₹ 8000 – ₹ 6000 = ₹ 2000

Time (T) = 4 years

∴ R = (S.I.×100)/P×T

=(2000×100)/(6000×4)

=25/3%

=8 (1/3)% p.a.

In second case, Principal (P) = ₹ 525

Amount (A) = ₹ 700

∴ S.I. = A – P = ₹ 700 – ₹ 525 = ₹ 175

Rate (R) = 25/3% of p.a.

∴ Time = (S.I.×100)/P×R

= (Rs.175×100×3)/(525×25)

= 4 years

Question 10.

The interest on a sum of money at the end of 2 years is  of the sum. What is the rate percent ?
Answer

Let the sum (P) = Rs. 100

∴ S.I. = Rs. 100×(4/5) = Rs. 80

Period (T) = 2 (1/2)

=5/2 years.

∴ Rate = (S.I.×100)/P×T

=(80×100×2)/(100×5)

= 32 % p.a.

Question 11.

What sum of money lent out at 5% for 3 years will produce the same interest as Rs. 900 lent out at 4% for 5 years ?
Answer

In second case, Principal (P) = Rs. 900

Rate (R) = 4%, Time (T) = 5 years

∴ S.I. = (P×R×T)/100

= (900×4×5)/100 = Rs. 180

In first case, S.I. = Rs. 180

Rate = 5 %, Time = 3 years

∴ Sum = (S.I.×100)/(R×T)

= (180×100)/(5×3)

= Rs. 1200

Question 12.

A sum of Rs. 1,780 become Rs. 2,136 in 4 years,
Find :
(i) the rate of interest.
(ii) the sum that will become Rs. 810 in 7 years at the same rate of interest ?
Answer

Question 13.

A sum amounts to Rs. 2,652 in 6 years at 5% p.a. simple interest.
Find :
(i) the sum
(ii) the time in which the same sum will double itself at the same rate of interest.
Answer

(i) Case First , Let principal (P) = rs. 100

Rate (R) = 5 % p.a., Time (T) = 6 years

∴  S.I. = (P×R×T)/100

= (100×5×6)/100

= Rs. 30

and, amount = Rs. 100 + Rs. 30 = Rs. 130

If amount is Rs. 130, then principal = Rs. 100

and, if amount is Rs. 2652, then principal

= (100×2652)/130

= Rs. 2040

(ii) Case second , Let sum (P) = Rs. 100

Amount (A) = Rs. 100 × 2 = Rs. 200

S.I. = A – P = Rs. 200 – 100 = Rs. 100

Rate = 5 % p.a.

Time = (S.I.×100)/(P×R)

= (100×100)/(100×5)= 20 years

Question 14.

P and Q invest Rs. 36,000 and Rs. 25,000 respectively at the same rate of interest per year. If at the end of 4 years, P gets Rs. 3,080 more interest than Q; find the rate of interest.
Answer

P’s investment (P₁) = Rs. 36000

and Q’s investment (P₂) = Rs. 25000

Period (T) = 4 years, Let rate of interest = x %

Q’s interest = Rs. (36000×x×4)/100

= Rs. 1440 x    (∵ S.I.=PRT/100)

and Q’s interest = (25000 × x × 4)/100

= Rs. 1000 x

Difference in their interest

= Rs. (1440 – 1000) x = Rs. 440 x

But difference = Rs. 3080

∴ 440 x = 3080 ⇒ x = 3080/440

⇒ x = 7%

∴ Rate of interest = 7 % p.a.

Question 15.

A sum of money is lent for 5 years at R% simple interest per annum. If the interest earned be one-fourth of the money lent, find the value of R.
Answer

Question 16.

The simple interest earned on a certain sum in 5 years is 30% of the sum. Find the rate of interest.
Answer

— End of Simple Interest Solutions :–

 

Return to – Concise Selina Maths Solutions for ICSE Class -7 

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