Aptitude - Ratio and Proportion - Discussion

Discussion Forum : Ratio and Proportion - General Questions (Q.No. 4)
4.
Seats for Mathematics, Physics and Biology in a school are in the ratio 5 : 7 : 8. There is a proposal to increase these seats by 40%, 50% and 75% respectively. What will be the ratio of increased seats?
2 : 3 : 4
6 : 7 : 8
6 : 8 : 9
None of these
Answer: Option
Explanation:

Originally, let the number of seats for Mathematics, Physics and Biology be 5x, 7x and 8x respectively.

Number of increased seats are (140% of 5x), (150% of 7x) and (175% of 8x).

140 x 5x , 150 x 7x and 175 x 8x
100 100 100

7x, 21x and 14x.
2

The required ratio = 7x : 21x : 14x
2

14x : 21x : 28x

2 : 3 : 4.

Discussion:
84 comments Page 7 of 9.

Subho said:   5 years ago
Math seats 5 increased will be 4% = now number of total seats 7. Physics seats 7 increased will be 50% = now number of total seats = 10.5. Bio seats 8 increased will be 75%= now the total number of state 14.

So, new seats ratio are 7:10.5:14.
= 2:3:4.

Himanshu said:   5 years ago
5:7:8 means 5/20 which means 0.25.

2:3:4 means 2/9 which means 0.22.

But it is saying that the seats have increased. But according to maths the seats have decreased.

Can anyone please tell me how is this possible?

Rahul said:   5 years ago
Let the ratio 500:700:800.
Increase 200:350:600.
700:105:1400=14:21:28=2:3:4 answer.
(2)

Priya said:   4 years ago
Nice explanation Mr. Harjinder Singh. Way to think in a simple manner.

Shiv said:   4 years ago
=>Maths : physics : Biology
=>. 5 : 7 : 8.
=> 5*140 : 7*150 : 8*175,
=>. 2 : 6 : 8.
(9)

Udit said:   4 years ago
How 7x:21/2x:14x =14x:21x:28x?

Anyone, please explain to me.

Shaik Babu said:   4 years ago
5 it is increased by 40%=5 * 40/100 = 2.
7 it is increased by50%=7 * 50/100 = 7/2.
8it is increased by 75%=8 * 75/100 = 6.
5+2=7/2+7 = 6 + 8.
7=21/2 = 14.
14=21 = 28.
2=3 = 4.
(61)

M Zubair said:   3 years ago
Excellent. Thanks all.
(2)

Ram Kundu said:   3 years ago
How it become 14x : 21x : 28x? Please explain this step.
(9)

Insaan said:   3 years ago
@Ram Kundu.

7x : 21x/2 : 14x from 14x : 21x : 28
To make the same denominator we have to multiply with 2 (7x*2/2 and 14*2/2)

14x/2 : 21x/2 : 28x/2 ( now we have the same denominator) we can ignore the denominator
Take LCM of 14x: 21x: 28x,
We get 2x: 3x: 8x.
(5)


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