Aptitude - Ratio and Proportion - Discussion

a:b = 2:3,
C:d = 5:8,
a:b:c= 10:15:24.
And 10+15+24 = 49 but their total given is 98.
So, we will multiply 49 by 2(because. Their total is 98 not 49) which will be 98.
Now; as in question they have asked to find the second number. So we will now multiply 15 by 2 = 30 answer.

How come 49?

B = 98 * 15/49.

Let the three numbers be x, y and z.
x : y : z
2 : 3
-----5 : 8.
= 10 : 15 : 24 (2*5 : 3*5 : 3*8).

= 10 + 15 + 24 = 49.
for B = 98 * 15/49,
=30.

Well said, Thanks @Kalpa.

@All.

Solution:

A: B = 2:3 and B: C = 5:8.
So Multiply A: B by 5 and B: C by 3.
So, we got a common B.

A: B = 10:15 and B: C = 15:24.

Total sum = 10+15+24 = 49,
Now, we want B so we simply.
B = (15/49)*Sum of total numbers (GIVEN).

B = (15/49)*98.
we get 30.

2:3
--5:8
_______
10:15:24
________
Now total sum is 98.
Then 10+15+24=49.
(98*15/49)=(2*15)=30.

x:y:z
2:3:3 ~1
5:5:8 ~2
Then multiply 1 and 2 we get 10:15:24.

10+15+24 = 98.
49 = 98.
1 = 2.
15x2 = 30.

A:B =2:3.
B:C = 5:8.
A:B:C = 10:15:24.

Therefore,
A=98*10/49;
B=98*15/49;
C=98*24/49;

Hence the result is easy.

2:3. 2*5=10. 5*3=15. 3*8=24
5:8. 15/49*98=30.
It is easy for time saving the exam.

let the 3 numbers be x,y,z.

Given is x:y = 2:3 and y:z = 5:8.

So from here we see that y is the common term in both the ratio.

When we will do now is make the value of "y" same in both the ratio.
so in the first ratio, we will multiply the x:y with 5 and the new ratio of x:y will become x:y = 10:15.

And similarly, in the second ratio, we will multiply the y:z with 3 and the new ratio of y:z will become y:z = 15:24
now from the above two newly formed ratio we see that the value of y is the same that is 15.

So from here, we can write the final ratio or proportion of x:y:z as 10:15:24.

So according to the given question, the sum of ratios of x,y,z is 98.

Threrefore, we can write: 10n + 15n + 24n = 98.
=> 49n =98,
=> n = 2,
Thus value of y(the second term) is = 15 n = 15 * 2 = 30.