i udn understand question.. help mi wif tis questions
Hello, xiaoz!
Seven men can paint a bridge in 15 days.
(1) How long woud it take 3 men?
One man can paint of the bridge in 15 days.
In one day, one man can paint of the bridge.
Hence, 3 men can paint of the bridge in one day.
Therefore, it will take the 3 men days to paint the bridge.
(2) The bridge was painted in days.
Write an expression, in terms of ,
for the number of men needed to paint the bridge.
Some information is missing . . .
Greetings Xiaoz:
If y varies directly with the square of x, then the relation between x and y is: y = kx^2, where k is a constant. Given y = 10 for some value of x, which I shall call xt, it follows that 10 = k(xt)^2. Now, dividing xt by 2 gives k(xt / 2)^2 on the right. And elimination of parentheses leaves k*(xt)^2 / 4. Hence dividing xt by 2 has the effect of dividing k(xt)^2 by 4. (This is only logical, yes? Dividing a squared quantity by 2 is equivalent to inserting factor, 1/2, within the 'squared parentheses'. The action yields 1/4 upon squaring). Anyway, if k(xt)^2 = 10, then it follows that [k(xt)^2] / 4 = 10/4 = 5/2 or 2.5.
I hope this was instructive.
Rich B.