Variations - JSS3 Mathematics Past Questions and Answers - page 1
If 𝑦 varies directly as 𝑥 and 𝑦=15 when 𝑥=3, what is 𝑦 when 𝑥=6?
30
45
15
18
If 𝑦 varies inversely as 𝑥 and 𝑦=10 when 𝑥=5, what is 𝑦 when 𝑥=8?
6.25
4
12.5
25
If 𝑧 varies jointly as 𝑥 and 𝑦, and 𝑧=24 when 𝑥=4 and 𝑦=3, what is 𝑧 when 𝑥=6 and 𝑦=5?
60
30
36
45
If 𝑧 varies partly as 𝑥 and inversely as 𝑦, and 𝑧=10 when 𝑥=5 and 𝑦=2, what is 𝑧 when 𝑥=10 and 𝑦=4?
5
20
2.5
40
If 𝑦 varies directly as 𝑥 and 𝑦=9 when 𝑥=6, find 𝑦 when 𝑥=12.
Given 𝑦=𝑘𝑥, substituting the given values:
9=𝑘⋅6
Solving for 𝑘:
𝑘=9/6=1.5
Now, find 𝑦 when
x=12:
𝑦=1.5⋅12=18
If 𝑦 varies inversely as 𝑥 and 𝑦=20 when 𝑥=4, find 𝑦 when 𝑥=5.
Given 𝑦=𝑘/𝑥, substituting the given values:
20=𝑘/4
Solving for 𝑘:
𝑘=20⋅4=80
Now, find 𝑦 when 𝑥=5:
𝑦=80/5=16
If 𝑧 varies jointly as 𝑥 and 𝑦, and 𝑧=36 when 𝑥=3 and 𝑦=4, find 𝑧 when 𝑥=6 and 𝑦=2.
Given 𝑧=𝑘𝑥𝑦, substituting the given values:
36=𝑘⋅3⋅4
Solving for 𝑘: 𝑘=36/12
=3
Now, find 𝑧 when 𝑥=6 and 𝑦=2:
𝑧=3⋅6⋅2=36