Find the fourth proportion of the following numbers:
3
1
rd of 27,
5
4
th of 30,
7
3
th of 35.
- A35
- B40
- C45
- D38
Solution & Step-by-step Explanation
Compute the three numbers first:
First number (a) =
3
1
×27=9
Second number (b) =
5
4
×30=24
Third number (c) =
7
3
×35=15
Let the fourth proportion be d. Then:
b
a
=
d
c
⟹
24
9
=
d
15
d=
9
24×15
=
3
24×5
=8×5=40
First number (a) =
3
1
×27=9
Second number (b) =
5
4
×30=24
Third number (c) =
7
3
×35=15
Let the fourth proportion be d. Then:
b
a
=
d
c
⟹
24
9
=
d
15
d=
9
24×15
=
3
24×5
=8×5=40