The DAV Class 7 Maths Solutions and **DAV Class 7 Maths Chapter 5 Worksheet 3** Solutions of Application of Percentage offer comprehensive answers to textbook questions.

## DAV Class 7 Maths Ch 5 WS 3 Solutions

Question 1.

I purchased a watch for ₹ 330 and sold it at a loss of 20%. Find S.P. of the watch.

Answer:

C.P. = ₹ 330, loss = 20%, S.P. = ?

S.P. = C.P. [1 – \(\frac{\text { loss }}{100}\)] = 330[1 – \(\frac{20}{100}\)]

= 300 × \(\frac{4}{5}\)

= 264

Question 2.

By selling a T.V. for ₹ 8000, a shopkeeper loses 20% of his cost. If he sells it for ₹ 11000, what profit or loss would be there for him?

Answer:

S.P. = T 8000, Loss = 20%, C.P. = ?

S.P. = C.P. (1 – \(\frac{\text { Loss }}{100}\))

8000 = C.P. × \(\frac{4}{5}\)

8000 = C.P. × \(\frac{20}{100}\)

C.P. = 8000 × \(\frac{4}{5}\) = ₹ 10,000

If S.P. = ₹ 11,000

∴ Profit = S.P. – C.P. = ₹ 11,000 – ₹ 10,000 = ₹ 1000

Hence the profit = ₹ 1000

Question 3.

A shopkeeper purchased a T.V. set for ₹ 9000 and sold it at a loss of 5%. Find the selling price of the T.V. Set.

Answer:

C.P. = ₹ 9000, loss = 5%, S.P. = ?

S.P = C.P[1 – \(\frac{\text { loss }}{100}\)]

= 9000(1 – \(\frac{5}{100}\))

= 9000 × \(\frac{19}{20}\)

= 450 × 19 = ₹ 8550

Hence S.P. = ₹ 8550

Question 4.

Seeta sells a dinning set to Neeta for ₹ 6000 and gains 20%, for how much should she sell it to increase her profit by another 5%?

Answer:

C.P. = ₹ 6000, gain 20%, S.P. = ?

S.P = C.P.(1 + \(\frac{\text { gain }}{100}\))

6000 = C.P. (1 + \(\frac{20}{100}\))

6000 = C.P. × \(\frac{6}{5}\)

C.P = 6000 × \(\frac{5}{6}\) = ₹ 5000

Profit = \(\frac{5}{100}\) × 5000 = ₹ 250

Total S.P. = ₹ 6000 + ₹ 250 = ₹ 6250

Question 5.

Ranjan bought a second hand scooter for ₹ 6000. He spent ₹ 300 on its repairs and sold it to vineet at a profit of 10%. Vineet sold the scooter to Mukesh at a loss of 10%. At what price did Mukesh buy the scooter?

Answer:

C.P. of Scooter for Ranjan = ₹ 6000

Money spent on repairing = ₹ 300

∴ Actual C.P. for Ranjan = ₹ 6000 + ₹ 300 = ₹ 6300

S.P. = C.P.( 1 +\(\frac{\text { Profit }}{100}\))

= 6300 (1 + \(\frac{10}{100}\)) = 6930

C.P. for Vineet = ₹ 6930

S.P. = C.P. (1 – \(\frac{\text { Loss }}{100}\)) = 6930 (1 – \(\frac{10}{100}\))

= 6930 × \(\frac{9}{10}\) = 6237

Hence Mukesh bought the scooter for ₹ 6237

Question 6.

A man buys two pens at ₹ 20 each. He sells one at a gain of 5% and other at a loss of 5%. Find his gain or loss %.

Answer:

C.P. of one pen = ₹ 20

gain = 5%

S.P = C.P.(1 + \(\frac{\text { gain }}{100}\))

= 20(1 × \(\frac{5}{100}\))

= 20 × \(\frac{21}{20}\)

= 21

C.P. of other pen = ₹ 20

loss = 5%

S.P. = C.P.(1 – \(\frac{\text { Loss }}{100}\))

= 20(1 – \(\frac{5}{100}\)) = 20 × \(\frac{19}{20}\) = ₹ 19

S.P. of the two pens = ₹ 21 + ₹ 19 = ₹ 40

C.P. of the two pens = ₹ 20 + ₹ 20 = ₹ 40

Hence there is no loss and no profit.

Question 7.

Mr. Tandon purchased a computer for ₹ 32000 and a microwave over for ₹ 6500. On computer, he lost 5% and on microwave he gained 15%. Find his total gain or loss percent.

Answer:

C.P. of a computer = ₹ 32000

C.P. of a microwave oven = ₹ 6500

For Computer, S.P = C.P(1 – \(\frac{\text { Loss }}{100}\)) = 32000(1 – \(\frac{5}{100}\))

= 32000 × \(\frac{19}{20}\)

= 1600 × 19

= ₹ 30400

For microwave oven, S.P = C.P.(1 + \(\frac{\text { gain }}{100}\))

= 6500(1 + \(\frac{15}{100}\))

= 6500 × \(\frac{23}{20}\)

= 325 × 23

= ₹ 7475

Combined C.P. = ₹ 32000 + ₹ 6500 = ₹ 38500

Combined S.P = ₹ 30400 + ₹ 7475 = ₹ 37875

C.P > S.P.

loss = ₹ 38500 – ₹ 37875 = ₹ 625

loss% = \(\frac{625 \times 100}{38500}=\frac{125}{77}\)% or 1\(\frac{48}{77}\)%

Hence the loss = 1\(\frac{48}{77}\)%

Question 8.

A sells a bicycle to B at a profit of 20% and B sells it to C at a profit of 25%. If C pays ₹ 1500, what did A pay for it?

Answer:

S.P. of bicycle for B = C.P. for C = ₹ 1500

S.P. = C.P. (1 + \(\frac{\text { Profit }}{100}\))

1500 – C.P. (1 + \(\frac{25}{100}\))

1500 = C.P. × \(\frac{5}{4}\)

C.P = 1500 × \(\frac{4}{5}\)

C.P. = ₹ 1200

C.P. for B = S.P. for A

S.P. = C.P.(1 + \(\frac{\text { Profit }}{100}\))

1200 -C.P.(1 + \(\frac{20}{100}\))

1200 = C.P. × \(\frac{6}{5}\)

⇒ C.P. = 1200 × \(\frac{5}{6}\)

= ₹ 1000

Hence the money paid by A = ₹ 1000