# NCERT Class 7 Mathematics Solutions: Chapter 8 –Comparing Quantities Exercise 8.3 Part 4

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1. Juhi sells a washing machine for. She loses in the bargain. What was the price at which she bought it?

Answer:

Selling price of washing machine

Loss percent

Consider the cost price of washing machine be .

Loss = Loss% of C.P

So,

So, the cost price of washing machine is .

2.

(i) Chalk contains Calcium, Carbon and Oxygen in the ratio. Find the percentage of Carbon in chalk.

(ii) If in a stick of chalk, Carbon is , what is the weight of the chalk stick?

Answer:

(i) Given ratio

Total part

Part of Carbon

Percentage of Carbon part in chalk

(ii) Quantity of Carbon in chalk stick

Consider, the weight of chalk be .

Then,

So, the weight of chalk stick is .