Page 230 - Start Up Mathematics_6

Solution: Cost of a dozen calculators = ` 720
Cost of 1 calculator = ` 60

Cost of 7 pilot pens = ` 315
Cost of 1 pilot pen = ` 45
Ratio of the cost of a calculator to the cost of a pilot pen = 60 : 45 = 4 : 3
Example 9: Consider the statement: The ratio of
breadth and length of a hall is 3 : 5. Breadth of the hall (in metres) 15 45
Complete the given table that shows Length of the hall (in metres) 25 50
some possible breadths and lengths of
the hall.
Breadth of the hall (in metres) 15 30 45
Solution: The ratio of breadth and length of a
hall is 3 : 5. Length of the hall (in metres) 25 50 75

Example 10: Divide 36 copies between Vineet and Neelu in the ratio of 4 : 5.
Solution: The sum of the two parts of the ratio = 4 + 5 = 9
It implies that out of 9 copies, Vineet will get 4 and Neelu will get 5.
4
Therefore, number of copies Vineet gets = cm × 36 = 16
9
5
and number of copies Neelu gets = cm× 36 = 20
9
Example 11: Mother wants to divide ` 36 between her daughters Shreya and Bhoomika in the
ratio of their ages. If Shreya is 15 years old and Bhoomika is 12 years old, find how
much Shreya and Bhoomika will get. (NCERT)
Solution: Age of Shreya = 15 years
Age of Bhoomika = 12 years

Total money to be divided = ` 36
The sum of two parts of the ratio = 15 + 12 = 27
It implies that if there are ` 27, Shreya will get ` 15 and
Bhoomika will get ` 12.
15
Therefore, Shreya gets = ` c m × 36 = ` 20
27
12
and Bhoomika gets = ` c m× 36 = ` 16
27
Example 12: The present age of Priya is 12 years. The age of Priya’s father is 42 years. Priya’s
mother is 6 years younger to her father. Find the ratio of:
(a) present age of Priya to her mother’s age.
(b) present age of Priya’s father to Priya’s mother.
(c) age of Priya to her mother when Priya’s age was 10 years.
(d) age of Priya’s father to the age of her mother 10 years ago.
Solution: Present age of Priya = 12 years
Present age of Priya’s father = 42 years

Present age of Priya’s mother = 42 – 6 = 36 years

222