What is the third proportional of 6 and 18?
- A48
- B54
- C36
- D42
Solution & Step-by-step Explanation
Let the third proportional of a and b be c. Then, by definition:
a:b::b:c⟹
b
a
=
c
b
⟹c=
a
b
2
Given values are a=6 and b=18. Substituting these into the formula:
c=
6
18×18
c=3×18=54
a:b::b:c⟹
b
a
=
c
b
⟹c=
a
b
2
Given values are a=6 and b=18. Substituting these into the formula:
c=
6
18×18
c=3×18=54