Selina solutions

Selina solutions

Grade 7

Simple Interest | Exercise 10

Question 1

Q1) Find the S.I. and amount on :

(i) Rs. 150 for 4 years at 5% per year.

(ii) Rs. 350 for 3\frac{1}{2} 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\frac{1}{2} % 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\frac{1}{2}% p.a.

(vii) Rs. 225 for 3 years 9 months at 16% p.a.

Solution:

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

∴ SI = \frac{PRT}{100}=\frac{150\times5\times4}{100}=Rs.30

And Amount = P + SI = 150 + 30 = Rs. 180

(ii) P = Rs. 350, R = 8% p.a

T = 3\frac{1}{2}years=\frac{7}{2}

∴SI=\frac{PRT}{100}=\frac{350\times8\times7}{100\times2}=Rs.98

Amount = P + SI = 350 + 98 = Rs. 448

(iii) P = Rs. 620

R = 8 p per rupee per month = 8% p.m

T = 4 months

∴ SI = \frac{PRT}{100}=\frac{620\times8\times4}{100}=\frac{19840}{100}=Rs.198.40

∴ Amount = P + SI

= 620 + 198.40 = Rs. 818.40

(iv) Principal (P) = Rs. 3380

Rate = 4\frac{1}{2}\%\ p.a=\frac{9}{2}\%

Period = 30 months = \frac{30}{12}years

SI=\frac{PRT}{100}=\frac{3380\times9\times30}{100\times2\times12}=\frac{1521}{4}=Rs.380.25

Amount = P + SI

= 3380 + 380.25 = Rs. 3760.25

(v) P = Rs. 600, R = 10% p.a

T = July 12 to Dec 5

July = 19 days

Aug = 31 days

Sep = 30 days

Oct = 31 days

Nov = 30 days

Dec = 05 days

Total = 146 days

=\frac{146}{365}=\frac{2}{5}years

∴SI=\frac{PRT}{100}=\frac{600\times10\times2}{100\times5}=Rs.24

∴ Amount = P + SI = 600 + 24 = Rs. 624

(vi) P = Rs. 850,

R = 2\frac{1}{2}\%=\frac{5}{2}\%\ p.a

T = 10th march to 3rd Aug

March = 21 days

April = 30 days

May = 31 days

June = 30 days

July = 31 days

Aug = 03 days

Total = 146 days

=\frac{146}{365}=\frac{2}{5}years

∴SI=\frac{850\times5\times2}{100\times2\times5}=Rs.8.50

∴ Amount = P + SI

= Rs . 850 + Rs. 8.50 = Rs. 858.50

(vii) P = Rs. 225, R = 16% p.a

T = 3 years 9 months

=3\frac{9}{12}=3\frac{3}{4}years=\frac{15}{4}years

∴SI=\frac{PRT}{100}=\frac{225\times16\times15}{100\times4}=Rs.135

∴ Amount = P + SI = Rs. 225 + Rs. 135 = Rs. 360

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Question 1

Q1) Find the S.I. and amount on :

(i) Rs. 150 for 4 years at 5% per year.

(ii) Rs. 350 for 3\frac{1}{2} 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\frac{1}{2} % 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\frac{1}{2}% p.a.

(vii) Rs. 225 for 3 years 9 months at 16% p.a.

Solution:

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

∴ SI = \frac{PRT}{100}=\frac{150\times5\times4}{100}=Rs.30

And Amount = P + SI = 150 + 30 = Rs. 180

(ii) P = Rs. 350, R = 8% p.a

T = 3\frac{1}{2}years=\frac{7}{2}

∴SI=\frac{PRT}{100}=\frac{350\times8\times7}{100\times2}=Rs.98

Amount = P + SI = 350 + 98 = Rs. 448

(iii) P = Rs. 620

R = 8 p per rupee per month = 8% p.m

T = 4 months

∴ SI = \frac{PRT}{100}=\frac{620\times8\times4}{100}=\frac{19840}{100}=Rs.198.40

∴ Amount = P + SI

= 620 + 198.40 = Rs. 818.40

(iv) Principal (P) = Rs. 3380

Rate = 4\frac{1}{2}\%\ p.a=\frac{9}{2}\%

Period = 30 months = \frac{30}{12}years

SI=\frac{PRT}{100}=\frac{3380\times9\times30}{100\times2\times12}=\frac{1521}{4}=Rs.380.25

Amount = P + SI

= 3380 + 380.25 = Rs. 3760.25

(v) P = Rs. 600, R = 10% p.a

T = July 12 to Dec 5

July = 19 days

Aug = 31 days

Sep = 30 days

Oct = 31 days

Nov = 30 days

Dec = 05 days

Total = 146 days

=\frac{146}{365}=\frac{2}{5}years

∴SI=\frac{PRT}{100}=\frac{600\times10\times2}{100\times5}=Rs.24

∴ Amount = P + SI = 600 + 24 = Rs. 624

(vi) P = Rs. 850,

R = 2\frac{1}{2}\%=\frac{5}{2}\%\ p.a

T = 10th march to 3rd Aug

March = 21 days

April = 30 days

May = 31 days

June = 30 days

July = 31 days

Aug = 03 days

Total = 146 days

=\frac{146}{365}=\frac{2}{5}years

∴SI=\frac{850\times5\times2}{100\times2\times5}=Rs.8.50

∴ Amount = P + SI

= Rs . 850 + Rs. 8.50 = Rs. 858.50

(vii) P = Rs. 225, R = 16% p.a

T = 3 years 9 months

=3\frac{9}{12}=3\frac{3}{4}years=\frac{15}{4}years

∴SI=\frac{PRT}{100}=\frac{225\times16\times15}{100\times4}=Rs.135

∴ Amount = P + SI = Rs. 225 + Rs. 135 = Rs. 360

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