Chapter 5: Operations on Rational Numbers Exercise – 5.4
Question: 1
Divide:
Solution:
Question: 2
Find the value and express as a rational number in standard form:
Solution:
Question: 3
The product of two rational numbers is 15. If one of the numbers is -10, find the other.
Solution:
Let the number to be found be x
x ×- 10 = 15
x = 15/(-10)
x = 3/(-2)
x = (-3)/2
Hence the number is x = (-3)/2
Question: 4
The product of two rational numbers is - 8/9. If one of the numbers is - 4/15, find the other.
Solution:
Let the number to be found be x
Hence the number is x = 10/3
Question: 5
By what number should we multiply -1/6 so that the product may be -23/9?
Solution:
Let the number to be found be x
Hence the number is x = 46/3
Question: 6
By what number should we multiply -15/28 so that the product may be -5/7?
Solution:
Let the number to be found be x
Hence the number is x = 4/3
Question: 7
By what number should we multiply -8/13 so that the product may be 24?
Solution:
Let the number to be found be x
x = - 39
Hence the number is x = - 39
Question: 8
By what number should -3/4 be multiplied in order to produce -2/3?
Solution:
Let the number to be found be x
x = 8/9
Hence the number is x = 8/9
Question: 9
Find (x + y) ÷ (x —y), if
Solution:
Question: 10
The cost of 7(2/3) metres of rope is Rs. 12(3/4). Find its cost per metre. 7(2/3) metres of rope cost = Rs. 12(3/4).
Solution:
Question: 11
The cost of 2(1/3) metres of cloth is Rs.75 1/4. Find the cost of cloth per metre. 2(1/3) metres of rope cost = Rs. 75(1/4)
Solution:
Question: 12
By what number should (-33)/16 be divided to get (-11)/4?
Solution:
x = 3/4
The number is x = 3/4
Question: 13
Divide the sum of (-13)/5 and 12/7 by the product of (-31)/7 and (-1)/2
Solution:
Question: 14
Divide the sum of 65/12 and 8/3 by their difference.
Solution:
Question: 15
If 24 trousers of equal size can be prepared in 54 metres of cloth, what length of cloth is required for each trouser?
Solution:
= 54/24
= 9/4 metres
9/4 metres of cloth is required to make each trouser