A and B run in opposite directions from a point P on a circle with different but constant speeds. A runs in anticlockwise direction. They meet for the first time at a distance of 900 m in clockwise direction from P and for the second time at a distance of 800 m in anticlockwise direction from P. If B is yet to complete one round, the circumference of the circle is a)1700m b)1250m c)1300m d)1200m

saraswathy
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Jun 11th, 2006
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uday

Jun 16th, 2006

1200

kingjaspe
Profile Answers by kingjaspe

Apr 19th, 2010

Ans is C i.e 1300

p is the perimeter of the circle
Suppose after t1 time they first met and a is the speed of A and b is the speed of B

a*t1=900
b*t1=-p+900 {p is minus for anti clock wise direction}

Suppose after time t2 they again met

b*t2=-800
a*t2= p+p -800 {extra p because the A is on its second round}

so from first set of equation

we have

a/b=900/(-p+900)

and from second set we have
a/b= (2p-800)/-800

so from these two equation compare their R.H.S

we have (2p-800)/-800 = 900/(-p+900)

cross multiply

then we have

-2psquare + 1800 p +800p = 0

simplify the equation we have

psquare - 1300p=0

finally we have p= 1300

tanuj

Nov 21st, 2011

Lets say the total perimeter is x.

When the first meeting happened A travelled 900m.

so b must have travelled x-900m.

while 2nd meeting happened A and B must have travelled same distance.

No when the distance given is 800 from anticlockwise=>which is the total distance travelled by B in two laps.

so total distance travelled by B is

2(x-900)=800

=>x=1300m

rinkatokarika

Sep 9th, 2014

in the given qt A is running anti clockwise ....the ans is correct but A travels x-900 mts and B travels 900 i guess