The sum of three numbers is 136. If the ratio between the first number and the second number is 2 : 3 and that between the second and the third number is 5 : 3, then the first number is:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 40
Two ratios that share a term are joined by making the common term (the second number) the same in both. It is 3 in the first ratio and 5 in the second, so both are scaled to make it 15.
First : second \(=2:3=10:15\)
Second : third \(=5:3=15:9\)
First : second : third \(=10:15:9\), a total of 34 parts
The 34 parts make 136, so one part \(=136\div34=4\)
The first number is 10 parts \(=10\times4=40\)