Selina solutions

Selina solutions

Selina solutions

Grade 7

CHAPTERS

3. Fractions (Including Problems)

4. Decimal Fractions (Decimals)

5. Exponents (including Laws of Exponents)

6. Ratio and Proportion (Including Sharing in a Ratio)

7. Unitary Method (including Time and Work)

11. Fundamental Concepts (Including Fundamental Operations)

12. Simple Linear Equations (Including Word Problems)

13. Set Concepts (Some Simple Divisions by Vedic Method)

14. Lines and Angles (Including Construction of angles)

17. Symmetry (Including Reflection and Rotation)

18. Recognition of Solids (Representing 3-D in 2-D)

Q13) 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.

Solution:

(i) In first case, Let principal (P) = Rs. 100

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

∴ SI = \frac{PRT}{100}=\frac{100\times6\times5}{100}=Rs.30

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

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

And, if amount is Rs. 2652 then principal

=\frac{100\times2652}{130}=Rs.2040

(ii)In second case, let sum (P) = Rs. 100

Amount (A) = 100 x 2 = Rs. 200

SI = A - P = 200 - 100 = 100 Rs.

Rate = 5% p.a

Time = \frac{SI\times100}{P\times R}=\frac{100\times100}{100\times5}=20\ years

Still have questions? Our expert teachers can help you out

Book a free class nowFractions (Including Problems)

Exponents (including Laws of Exponents)

Ratio and Proportion (Including Sharing in a Ratio)

Unitary Method (including Time and Work)

Fundamental Concepts (Including Fundamental Operations)

Simple Linear Equations (Including Word Problems)

Set Concepts (Some Simple Divisions by Vedic Method)

Lines and Angles (Including Construction of angles)

Symmetry (Including Reflection and Rotation)

Recognition of Solids (Representing 3-D in 2-D)

Q13) 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.

Solution:

(i) In first case, Let principal (P) = Rs. 100

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

∴ SI = \frac{PRT}{100}=\frac{100\times6\times5}{100}=Rs.30

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

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

And, if amount is Rs. 2652 then principal

=\frac{100\times2652}{130}=Rs.2040

(ii)In second case, let sum (P) = Rs. 100

Amount (A) = 100 x 2 = Rs. 200

SI = A - P = 200 - 100 = 100 Rs.

Rate = 5% p.a

Time = \frac{SI\times100}{P\times R}=\frac{100\times100}{100\times5}=20\ years

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