Aptitude - Ratio and Proportion - Discussion

x+y+z = 98;--> eq.1

x/y = 2/3;
y/z = 5/8;

x = (2y/3);
z = (8y/5).

Substituting new value of x and z in eq 1,
=> (2y/3)+y+(8y/5)=98;

Taking LCM as 15;
=> (10y+15y+24y)/15=98;
=> 49y=98*15;
=> y=(98*15)/49;
=> y=2*15;
=> y=30.

Please tell me the easy way to solve this problem?

Instead of doing as per some formula you can solve this question right from the options given below let me explain,

See the question " If the ratio of the first to second is 2 :3 and that of the second to the third is 5 : 8 ".

* They are asking the value of B only so whose part is 3 and 5 so if you look into the option only the number 30 will be divided by both 3 and 5 whereas other option can't just try with this method it may be useful to you.

CROSS CHECKING THE ANSWER : If B is 30 then A will be 20 and C will be 48 so by adding this (20 + 30 + 48 = 98).

Solution correct !

A:B = 2:3.
B:C = 5:8.

By short cut we get,
A:B:C = 10:15:24.

How we get is by using above ratios,

A's value = A*B.
B = B*B.
C = B*C...

Then as given in problem,

10x+15x+24x = 98.
49x = 98.
x = 2..

So, 15x = 15*2 = 30.

Explain the whole problem clearly and step by step.

A:B = 2:3.
B:C = 5:8.

(2:3)x5 = 10:15.
(5:8)x3 = 15:24.

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

Let the ratio of numbers be 10x:15x:24x.

According to question,

10x+15x+24x = 98.

49x = 98.

x = 98/49.

x = 2.

Now 2nd number is 15x.

i.e;15*2 = 30.

If a:b=m:n and b:c=p:q then a:b:c= mp:np:nq.

Here,

a:b=2:3 .
b:c=5:8.

Then a:b:c become 10:15:24.

If sum of money S is divided in the ratio a:b:c then part of b is

= (b/a+b+c)*S.

Now here part of B become (15/49)*98 = 30.

@jay namdev we have Rs.58.

IN 58 25 paise is = 58*4 = 232.
In 58 50 paise is = 58*2 = 116.

Ratio of 50 paise : 25 paise 1:2.
Total 150 student it means if boys is 50 then girls is 100.
100+50 =150.

It means total girls in class is 100.

A:B = 2:3.
B:C = 5:8.

(2:3)x5 = 10:15.
(5:8)x3 = 15:24.

A:B:C = 10:15:24.
So the second number(B) is: (98*15/49) = 30.

I have a question please solve it. If A:B=2:3, B:C=4:5, and C:D= 6:7 then find the value of A:B:C:D.