Aptitude - Ratio and Proportion - Discussion

Discussion Forum : Ratio and Proportion - General Questions (Q.No. 9)
9.
The sum of three numbers is 98. If the ratio of the first to second is 2 :3 and that of the second to the third is 5 : 8, then the second number is:
20
30
48
58
Answer: Option
Explanation:

Let the three parts be A, B, C. Then,

A : B = 2 : 3 and B : C = 5 : 8 = 5 x 3 : 8 x 3 = 3 : 24
5 5 5

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

B = 98 x 15 = 30.
49

Discussion:
122 comments Page 5 of 13.

Sweet said:   1 decade ago
Let a's amount= z
so b's amount=1210-z
now (4/15)z=(2/5)x(1210-z)
=>
(4/15)z=484-2/5z
=>
(4/15)z+(2/5)z=484
=>
by taking l.c.m (10/15)z=484
=> 10z=7260
=>
z=726

So a's amount=z=726

and b's amount=1210-726=484 ans.

Ankur saxena said:   1 decade ago
a/b=2/3,b/c=5/8
a+b+c=98
2b/3+b+8b/5=98
b=30

Murali said:   1 decade ago
If a:b:c=2:3:5 then the ratio of (b+c)/4:(c+a)/4:(a+b)/4 is?
Can any one give answer for this....

RISHIKESH said:   1 decade ago
Thanks alisha.

Nisha said:   1 decade ago
Thanks kalpa.

Deepi said:   1 decade ago
SEE This carefully
a:b1
- b2:c
-----------
a*b2:b1*b2:b1*c=a:b:c

JAY NAMDEV said:   1 decade ago
There are 150 students in a class, we have only 58 rupees, if we distribute 25p and 50p amongst girls and boys respectively then what no of girls?

Veena said:   1 decade ago
x:y=2:3 --->1
y:z=5:8 --->2
multiply with 5 in equation 1
10:15
in equation 2 multiply with 3
15:24

10:15:24

15--?
49--98
15/49x98=30

POORNI said:   1 decade ago
THANKS APARNA

Rajkumar said:   1 decade ago
General formula

A:B
B:C
---------------
A*B : B*B : B*C
----------------
A*B + B*B + B*C = sum

Then total should be divided with this sum

Ans = total / sum

This ans should be multiplied with each ratios to get a desired number

In the same way

2:3
5:8
-------
10:15:24 (2*5 : 3*15 : 3*8)

Then adding 10+15+24 gives 49

This 49 divides 98

98 / 49 = 2

B = 2*15 = 30

Similarly

A = 2 * 10 = 20

C = 2 * 24 = 48


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