MathRevolution wrote:

[GMAT math practice question]

The relationship between the cost (c) and time (t) is given by the equation \(c=mt+b\). If the time is increased by \(10\), by how many dollars is the cost increased?

\(1) m=20\)

\(2) b=30\)

Original cost = \(mt+ b\).

When the time increases by 10, we get:

New cost = \(m(t+10) + b = mt + 10m + b\).

Thus:

Increase in the cost = new cost - original cost = \((mt + 10m + b) - (mt + b) = 10m\).

To determine the increase in the cost, we need to know the value of \(m\).

Question stem, rephrased:

What is the value of \(m\)?Statement 1: \(m=20\)

SUFFICIENT.

Statement 2: \(b=10\)

No information about m.

INSUFFICIENT.

_________________

GMAT and GRE Tutor

Over 1800 followers

Click here to learn more

GMATGuruNY@gmail.com

New York, NY

If you find one of my posts helpful, please take a moment to click on the "Kudos" icon.

Available for tutoring in NYC and long-distance.

For more information, please email me at GMATGuruNY@gmail.com.