Home » Aptitude » Ratio, Proportion » Question
  1. Two numbers are in the ratio 3 : 5. If 9 is subtracted from each, then they are in the ratio 12 : 23. Find the smaller number.
    1. 27
    2. 33
    3. 49
    4. 55
Correct Option: B

Let the numbers be 3x and 5x.

∴ 
3x − 9
=
12
5x − 923

⇒  69x – 60x = 207 – 108
⇒  x =
99
= 11
9

∴  The smaller number
= 3x = 33
Second Method :
Here, a = 3, b = 5, x= 9, c = 12, d = 23
1st Number =
xa(d − c)
ad − bc

=
9 × 3(23 − 12)
3 × 23 − 5 × 12

=
27 × 11
69 − 60

=
27 × 11
= 33
9

2nd Number=
xb(d − c)
ad − bc

=
9 × 5(23 − 12)
3 × 23 − 5 × 12

=
45 × 11
69 − 60

=
45 × 11
= 55
9

∴  Smallest number = 33



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