The time taken for a

committee meeting is partly
constant and partly varies as the
square of the number of members
present. If there are fifteen
members present, the meeting
lasts only 45 minutes, but with
twenty-five it takes exactly 2hrs
15 minutes. How long will it last if
there are thirty members there?
A. 3hrs
B. 3hrs 17mins
C. 2hrs 19mins
D. 1 hr 18mins

1 answer

Let's assume the constant time for the committee meeting is x minutes and the time that varies with the square of the number of members present is y minutes.

From the given information, we can form two equations:

Equation 1: x + 15^2 * y = 45
Equation 2: x + 25^2 * y = 135

Simplify equation 1:
x + 225y = 45

Simplify equation 2:
x + 625y = 135

Subtract equation 1 from equation 2 to eliminate x:
625y - 225y = 135 - 45
400y = 90
y = 0.225

Substitute y value back into equation 1 to find x:
x + 225 * 0.225 = 45
x + 50.625 = 45
x = 45 - 50.625
x = -5.625

Now, we have the values of x = -5.625 and y = 0.225. We can use these values to find the time for 30 members.

Equation 3: -5.625 + 30^2 * 0.225 = t
-5.625 + 900 * 0.225 = t
-5.625 + 202.5 = t
t = 196.875

Therefore, the meeting will last approximately 196.875 minutes, which is equal to 3 hours and 16.875 minutes. Rounding to the nearest minute, the answer is:

B. 3 hours 17 minutes