Page 118 - Maths Skills - 8

116 Maths

11. A number is increased by 5% and then decreased by 5%. Find the net increase or decrease per cent.

12. A person deposits ` 2400 per month in his savings bank account. If this is 15% of his monthly income,
find his monthly income.
13. The strength of students in a college increases by 6%. If the actual increase in the number of students
is 240, find the original strength of the school.
14. If a teacher’s salary is increased by 8% and the new salary is ` 13500, what was his previous salary?

15. A number is increased by 30% and then it is decreased by 30%. Find the net increase or decrease
per cent.

1
16. After incurring a loss of 45 %, a person is left with ` 10355. Find the amount he originally had.
2
17. The value of a machine depreciates every year by 15%. If the present value of the machine is ` 150000,
what will be its value after 3 years?

18. The value of a car reduces by 20% every year. If the value of a new car is ` 350000, find its value after
2 years.
19. A mixture of milk and water contains 8 parts of milk and 2 parts of water. Find the percentage of milk
and water in the mixture.

20. Find:
(i) 12% of 75 (ii) 120% of `30 (iii) 75% of 8 m

DISCOUNT
When we visit a shop, we find that every sale article has its price marked on it or its price is mentioned on a card
or a label. This price is known as marked price (M.P.) of the article.
At times in order to clear the stocks or to increase the sales the shopkeepers offer a certain percentage of rebates on
the marked price of an article. This rebate is known as the discount. In such case the customer pays the difference
of the marked price and the discount allowed.

Thus, Selling Price = Marked Price – Discount
Absorbing Facts
Selling Price = Marked Price – Discount Discount is always calculated

on the marked price.
Discount
Discount % = × 100
M.P.
Successive Discounts
The discounts allowed one after the other on an article are called successive discounts.

For example, 20% discount is given on an article and after that a 10% discount is given on the reduced price.
Then, successive discounts of 20% and 10% are allowed on the article.

Now, let us learn through examples.