Question

Tim explained a function in words and Paul wrote an equation.

Tim

The amount of money in a savings account increases at a rate of $225 per month. After eight months, the bank account has $4,580 in it.

Paul

y−1,400=56(x+26)

Whose function has the smaller y-intercept?

Tim’s with a y-intercept of $2,700
Paul’s with a y-intercept of $2,856
Paul’s with a y-intercept of $2,800
Tim’s with a y-intercept of $2,780

Answer 1

Tim: y = 225x + b. 225(8) + b = 4580 → 1800 + b = 4580 → b = 2780.

Paul: y − 1400 = 56(x + 26). At x = 0, y = 1400 + 56·26 = 1400 + 1456 = 2856.

Smaller y-intercept is Tim’s: $2,780.