Page 178 - Start Up Mathematics_8 (Non CCE)

3. A certain medicine contains 76.4% of absolute alcohol, 2.9% of mentha oil, 1.02% of spearmint oil and
0.25% of chloroform. What is the amount (in mL) of each compound in a pack of 30 mL? Is it safe to
take medicines without consulting a doctor?
4. In an election, there were only two candidates. The winner polled 55% votes and won by 8,900 votes.
Find the total number of votes polled. Do you think that there are free and fair elections in India?
5. Kairvini went to school for 225 days in a full year. If her attendance is 90%, find the number of days on
which the school was opened. Do you think your school should award students with 100% attendance?
6. In the new budget, the price of pulses increased by 12%. By how much percent must one reduce the
consumption so that the expenditure does not increase? Do you think it is beneficial to make a budget to
keep a check on household expenses?

Some NCERT Textbook Questions

1. A football team won 10 matches out of the total number of matches they played. If their win percentage
was 40 then how many matches did they play in all?
2. If Chameli had ` 600 left after spending 75% of her money, how much did she have in the beginning?
3. If 60% people in a city like cricket, 30% like football and the remaining like other games, then what per
cent of the people like other games? If the total number of people are 50 lakh, find the exact number who
like each type of game.
4. A man got a 10% increase in his salary. If his new salary is ` 1,54,000, find his original salary.

Exemplar Problems

1. 40% of [100 – 20% of 300] is equal to:
(a) 20 (b) 16 (c) 140 (d) 64
2. Radhika bought a car for ` 2,50,000. Next year its price decreased by 10% and further next year it
decreased by 12%. In the two years overall decrease percent in the price of the car is:
(a) 3.2% (b) 22% (c) 20.8% (d) 8%
3. Percentages are ___________ to fractions with ___________ equal to 100.
4. Four times a number is a ___________ % increase in the number.
5. Three times a number is 200% increase in the number, then one-third of the same number is 200% decrease
in the number. (True/False)
6. An average urban Indian uses about 150 litres of water everyday.
Activity Litres per person per day
Drinking 3
Cooking 4
Bathing 20
Sanitation 40
Washing clothes 40
Washing utensils 20
Gardening 23
Total 150
(a) What percent of water is used for bathing and sanitation together per day?
(b) How much less percent of water is used for cooking in comparison to that used for bathing?
(c) What percent of water is used for drinking, cooking and gardening together?
7. The population of a town was decreasing every year due to migration, poverty and unemployment. The
present population of the town is 6,31,680. Last year the migration was 4% and the year before last, it
was 6%. What was the population two years ago?
170