Enter your email address:


November 10, 2009

Find the length of the bridge ?



There is a river which is 4100 inches wide, and the bridge across the
river is in such a way that one seventh of the overall length of the
bridge was on one side of the river and one eighth of the bridge was
on the other side of the river.
Find the total length of the bridge?

[Note: The bridge perfectly straight]

6 comments:

paul.hindess said...

Assuming I'm correct, this a spoiler...

Giving the answer as the difference of two squares (don't calculate this if you want to solve it for yourself!)

75^2 - 5^2

Can someone confirm (or deny) my answer?

Anonymous said...

to me u r right....

Manjitha said...

manju
bridge is 5600m long

Varun said...

Suppose length is X.

X- (X/7) - (X/8) = 4100

X= 5600

19reka said...

Agree, it is 5600. My only comment is that it's not metres, but inches. Minor detail.

My way of thinking:
Bridge's length:
1/7 of length
1/8 of length
4100 inches of length

x = 1/7x + 1/8x + 4100 /*7
7x = x + 7/8x + 4100*7 /*8
56x = 8x + 7x + 4100*56
56x - (8x + 7x) = 4100 * 56
41x = 4100 * 56
x = 100 * 56 = 5600

Question to paul.hindess:
Can you share your way of thinking (75^2 - 5^2)? :)

19reka said...

Answer to question I asked paul.hindess: I got it...
(a-b)2 = a2 - 2ab + b2
(75^2 - 5^2) :)