Word Problem

[Kyle Concannon]

Please help me.

One of the dangers of coal mining is the methane gas that can leak out of seams in the rock. Methane forms an explosive mixture with air at a concentration of 5% or greater, A steady leak of methane begins in a coal mine such that the concentration of methane gas vaires directly as time. Twelve minutes after the leak begins, the concentration of methane in the air is 2%. If the leak continues at the same rate, when could an explosion occur?

 

[stapel]

Variation problems translate as follows:

. . . . ."y varies directly as x": y = kx

. . . . ."y varies inversely as x": y = k/x

. . . . ."y varies jointly as x and z": y = kxz

Translate "the methane concentration varies directly as time" into a variation equation, using variables such as M and t, with k being the constant of variation.

Note that they've given you that, at t = 12, the concentration M is 0.02. Use this to solve for the value of k.

Then plug in "0.05" for "M", and solve for the time t in minutes.

Then run like heck, before the thing blows. :wink:

Eliz.