Question

A phone company offers two monthly charge plans. In plan a, there is no monthly fee, but the customer pays 7 cents per minute of use. In plan b, the customer pays a monthly fee of 3.40 and then an additional 5 cents per minute of use. For what amounts of monthly phone use will plan a cost more than plan b

Answer 1

Answer:

Step-by-step explanation:

Plan A: y = 25 + .06m

Plan B: y = 29.70 + .05m

25 + .06m < 29.70 + .05m

.01m < 4.7

m < 470 minutes

Answer 2

For a monthly use of phone calls more than 170 minutes, plan a will cost more than plan b.

Step-by-step explanation:

In plan a, the customer pays 7 cents per minute of use with no monthly fee.

So, the cost of x minutes call is given by, y = 0.07x ............. (1)

Again, in plan b, there is a charge of 5 cents per minute of use and in addition, the customer pays a monthly fee of 3.40.

So, the cost for x minutes call is given by, y = 3.4 + 0.05x  ........... (2)

Now, we have to find the value of x for which plan a costs plan b will be

0.07x > 3.4 + 0.05x

⇒ 0.02x > 3.4

⇒ x > 170 minutes.

So, for monthly use of phone calls more than 170 minutes, plan a will cost more than plan b. (Answer)