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:
82 comments Page 1 of 9.

Shwetha said:   1 decade ago
Why is the %age value changing from 40 to 140, 50 to 150 and 75 to 175 ?

Can anyone explain in detail please?

Malli said:   1 decade ago
Because initial amount is 100 then 100+40=140 etc.

Praveen said:   1 decade ago
Any shortcut for this ?

Richa said:   1 decade ago
@ shwetha

when it is said that there is x% or y% increase in any value then to find out that increased value we have do
100+x

as in this example a value increased 40% means 100+40=140

Ramesh said:   1 decade ago
5:7:8 = 50:70:80
50*140/100=70 ; 70*150/100=105 ; 80*175/100=140
70: 105: 140 or
14: 21: 28 or
2: 3: 4

Hari said:   1 decade ago
Good shortcut ramesh.

Vivek mishra said:   1 decade ago
Thanks to giving a good salution with shortcut.

Sandi said:   1 decade ago
Very good shortcut ramesh.

Mariah said:   1 decade ago
Can we apply this shortcut for other problems?

Harjinder Singh said:   1 decade ago
1. 40% of 5 = 2, total seats 5+2=7
2. 50% of 7 = 7/2 total seats 7+7/2=21/2
3. 75% of 8 = 6 total seats 8+6=14
now compare ratios of all 7:21/2:14=>14:21:28
=>2:3:4


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