Latest IBM Aptitude Question SOLUTION: Three numbers A,B,Care in ratio 1:2:3. Their average is 600. If A is increased by 10% and B is increased by 20%, then to get the average increased by 5%, C will increased by: a)90

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(#M40151596) IBM Numerical Ability question Ratio and proportion Keep an EYE

Three numbers A,B,Care in ratio 1:2:3. Their average is 600. If A is increased by 10% and B is increased by 20%, then to get the average increased by 5%, C will increased by:
a)90
b)100
c)150
d)180

Asked In IBM tushar (9 years ago)

Unsolved Read Solution (15)

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Read Solution (15) :

Ganesh  (9 years ago)

TUSHAR you took B to be reduced by 20% instead of increasing it.


Taking A= x, B=2x, and C=3x.
(x+2x+3x)/3=600
x=300

so, the numbers are 300,600,900

new average= 105%of 600= 630

so (110% of 300 + 120% of 600 + x)/3 = 630

330 + 720 + x = 1890
x= 1890 - 1050
x=840

so C should be reduced by 60 or 6.66%

HENCE THE QUESTION IS WRONG

Is this solution Helpfull? Yes (39) | No (5)  

MD EQUBAL HUSSAIN  (9 years ago)

question is not correct 100 % if correct then , C have to decressed by 6.66 % not increased .....

Is this solution Helpfull? Yes (7) | No (4)  

tushar  (9 years ago)

Let be A= x, B=2x, and C=3x.
(x+2x+3x)/3=600
this will be x=300

so, the numbers will be 300,600,900

new average= 105%of 600= 630

Let 110% of 300+80% of 600 + y= 630*3

solve it for y, you will get, y=1080

so, increase in C= 1080-900 =180 ans

Is this solution Helpfull? Yes (7) | No (17)  

umesh  (8 years ago)

Ler numbers be A = x, B = 2x and C = 3x
Average = (x + 2x + 3x)/3 = 600
6x = 3 × 600 = 300
A = 300, B = 600, C = 900
A increased by 10% then A = 300 × 110/100 = 330
B decreased by 20% then B = 600 × 80/100 = 480
Average increased by 5% then new average = 600 × 1.05 = 630
The total of new A, B, C
= (330 + 480 + C)
New average = (330 + 480 + C)/3 = 630
810 + C = 630 × 3
C = 1080

increase of C = (1080 – 900) = 180 ---------- D

Is this solution Helpfull? Yes (7) | No (2)  

sanjana  (9 years ago)

guys if you want 180 as the ans then the question is to be changed as B is decreased by 20%.....otherwise reduced by 60 would be the right answer

Is this solution Helpfull? Yes (3) | No (1)  

arpitadas  (9 years ago)

i too thnk ques is not correct

Is this solution Helpfull? Yes (2) | No (1)  

sandeep  (8 years ago)

if b is increased by 80% then
Let be A= x, B=2x, and C=3x.
(x+2x+3x)/3=600
this will be x=300
so, the numbers will be 300,600,900
new average= 105%of 600= 630
Let 110% of 300+80% of 600 + y= 630*3
solve it for y, you will get, y=1080
so, increase in C= 1080-900 =180 ans

Is this solution Helpfull? Yes (2) | No (3)  

sandeep  (8 years ago)

if b is decreased by 20% then
Let be A= x, B=2x, and C=3x.
(x+2x+3x)/3=600
this will be x=300
so, the numbers will be 300,600,900
new average= 105%of 600= 630
Let 110% of 300+80% of 600 + y= 630*3
solve it for y, you will get, y=1080
so, increase in C= 1080-900 =180 ans

Is this solution Helpfull? Yes (2) | No (1)  

umesh  (8 years ago)

B is decreased by 20%, Ans will be.. d) 180

question is wrong.. ...

Is this solution Helpfull? Yes (2) | No   

pratiksha soni  (9 years ago)

yes if it is redused by 20% then the answer would be 180 otherwise it will be 60

Is this solution Helpfull? Yes (1) | No   

manisha shete  (7 years ago)

A,B,C =1:2:3
Therefore ,A=x,B=2x,C=3x
their average is 600
x+2x+3x=600*3
6x=1800
x=300
A=300,B=600,C=900
If A is increased By 10%=110/100* 300=330
IF b is deacreased by 20% =80/100* 600=480
Average is increased by 5% =105/100*600= 630
therefore 330+480+C=630*3
810+C=1890
C=1080

so C is increased By 1080-900=108

Is this solution Helpfull? Yes (1) | No   

tushar  (9 years ago)

answer is d)180
and question is absolutely RIGHT.

Is this solution Helpfull? Yes | No (7)  

saikrishna  (9 years ago)

can u explain how u got 180 as answer

Is this solution Helpfull? Yes | No (1)  

Techie  (9 years ago)

plz explain tushar..!

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amaresh  (7 years ago)

Ans:
180
180

Total of A,B,C
=
600
×
3
=
1800
=600×3=1800

A
=
1800
×
1
6
=
300
=1800×16=300
B
=
300
×
2
=
600
=300×2=600
C
=
300
×
3
=
900
=300×3=900

New average
=
600
+
600
×
5
100
=
630
=600+600×5100=630
New Total
=
3
×
630
=
1890
=3×630=1890

New value of A
=
300
+
300
×
1
10
=
330
=300+300×110=330
New value of B
=
600
−
600
×
1
5
=
480
=600−600×15=480

New value of C
=
1890
−
330
−
480
=
1080
=1890−330−480=1080
Increase in the value of C
=
1080
−
900
=
180
=1080−900=180

Note:
Since average increases by
5
%
5%, total also increases by
5
%
5%. Therefore, new total can be directly found as
1800
+
1800
×
5
100
=
1890

Is this solution Helpfull? Yes | No (1)  

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