Exercise 7.1
- Find the ratio of the following. (a) Speed of a cycle 15 km per hour to the speed of scooter 30 km per hour. (b) 5 m to 10 km (c) 50 paise to Rs. 5
(a) Speed of cycle : Speed of Scooter =
Hence, the ratio = 1 : 2
(b) 5 m : 10 km = 5 m : 10 ×
Hence, the ratio = 1 : 2000
(c) 50 paise : ₹ 5 = 50 paise : 5 ×
Hence, the ratio = 1 : 10
- Convert the following ratios to percentages:
(a) 3 : 4 (b) 2 : 3
(a) 3 : 4 =
(b) 2 : 3 =
- 72% of 25 students are interested in mathematics. How many are not interested in mathematics?
Number of students who are good in mathematics = 72 % of 25 =
Number of students who are not good in mathematics =
Thus, 7 students are not interested in mathematics.
- 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?
Unitary Method: 40 matches the team won out of 100 matches which means 1 match was won out of
Thus, 10 matches the team will won out of 100 40
Hence, the total number of matches played by the team = 25
- If Chameli had Rs. 600 left after spending 75% of her money, how much did she have in the beginning?
Assume the money with Chameli to be ₹ 100. Thus, Money spent by her = 75 % of
The money left with her = ₹
Thus, ₹ 25 are left with her out of ₹ 100 which means that ₹ 1 is left with her out of ₹
So, ₹ 600 will be left out of ₹ 100 25
So, Chameli had ₹ 2400 with her in the beginning.
- 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 is 50 lakh, find the exact number who like each type of game.
Total number of people =
So, number of people who like cricket = 60 % of 5000000 =
Number of people who like football = 30% of 5000000 =
Number of people who like other games = 5000000 – (3000000 + 1500000) = 5000000 –
Percentage of the people who like other games =
Hence, 10% of people like other game.