Latest TCS Aptitude Question SOLUTION: There is a circular pond and there is a road around the pond. The road is 4ft wide. The area of the pond is 11/25 of the area of the road. What is the radius of the pond?

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There is a circular pond and there is a road around the pond. The road is 4ft wide. The area of the pond is 11/25 of the area of the road. What is the radius of the pond?

Asked In TCS Parijat Mukherjee (11 years ago)

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Lucy kumari  (11 years ago)

let radius of pond=r
then,radius of road=r+4
since area of pond=11/25(area of road)
pi r^2=11/25 pi[(r+4)^2-r^2]
after solving this equa we get
25r^2-88r-176=0
r=4.94

Is this solution Helpfull? Yes (15) | No   

mukesh gupta  (11 years ago)

x=4.9 is ans

Is this solution Helpfull? Yes (8) | No (1)  

Mastik Kumar  (11 years ago)

let radius of pond ...a
area of pond = pi*a2
let radius of road from centr of pond is ...b
so area of road is = pi(b2-a2)
acc. to problem
(11/25)(pi*a2)=pi(b2-a2)
so (36/25)a2=b2
(6/5)a=b...........(lenght cant be -ve)
given width of road is 4feet....
b=a+4
so a=20
radius of pond is 20feet

Is this solution Helpfull? Yes (6) | No (6)  

Devi.S  (11 years ago)

Road area a= pi(r+4)^2 - pi r^2
pool area b=pi r^2
11/25=a/b
solve the above one & you get the radius of the pond...

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

dinesh gupta  (11 years ago)

area of pond =1125area of road
pi*x^2=1125(pi*(x+4)^2-pi*x^2)
solve x=1.5

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

Amardip Gautam  (11 years ago)

let radius of pond is r then
radius of road is=(r+4)-r=4
so
r^2/(((r+4)^2))-r^2)=11/25
so,(((r+4)^2))-r^2)/r^2=25/11
applying componendo and dividendo,
((((r+4)^2))-r^2)/r^2)+1=(11/25)+1
((r+4)^2)/r^2=33/11
3*r^2=(r+4)^2
((r+4)^2)-3r^2=0
r+4+underroot3=0
and r+4- underroot3=0
solving,r=4-underroot3 or r=4+underroot 3

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

soumik banerjee  (11 years ago)

4.26*sqrt{(25*8)/11}

Is this solution Helpfull? Yes | No (2)  

BALENDU NARAIN PANDEY  (11 years ago)

approx 4.984 let radius of pond be r then radius of bigger circle be r+4
so using r^2=11/25*((r+4)^2-r^2) we get r=4.984

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