Find the fourth proportional of 12,20 and 3.
Answers
Answer:
5
Step-by-step explanation:
a:b=c:d
a/b=c/d
12/20=3/d
12×d=3×20
d=3×20/12
d=20/4
d=5
Given:
The numbers 12, 20, 3, and one other number are in proportion.
To Find:
The value of the other number such that the 4 numbers are in proportion?
Solution:
The given problem can be solved using the concepts of proportion.
1. The given numbers are 12, 20, 3. Let the 4th unknown number be x.
=> The numbers 12, 20, 3, and x are in proportion.
2. Consider 4 numbers a, b, c, and d. The four numbers are said to be in proportion only when, a:b = c:d,
=> The ratio of a and b must be equal to the ratio of c and d.
=> If a, b, c, and d are in proportion, then we can use the relation a:b:: c:d.
3. Using the above property, the value of the unknown number can be determined.
=> 12 : 20:: 3:x,
=> 12/20 = 3/x,
=> 3/5 = 3/x,
=> 1/5 = 1/x,
=> x = 5.
Therefore, the value of the fourth proportional is 5.