An overseas telephone company charges $4 for the first minute of talking and then $0.25 for each additional minute. If a woman spent $13.75 talking on the phone, how many minutes did she talk for?

Step-by-step explanation:

In this problem we can see that there is a constant/flat rate charge of $4 on every first minute

we can model the cost for calls as

where x is the number of extra minutes spent

given that y = $13.75

We can simply substitute our given values into the equation 1 above and solve for x

Divide both sides by 0.25 to find x

the answer   is 200

step-by-step explanation:

this is a problem about poisson probabilities.   i don't know if you've

already studied poisson distributions, or if you have a place to look

to read more about the subject.  

here's how you can see a poisson distribution coming.   when there are

a lot of events that may happen at any time (or any place), and when

you're counting how many of them happen at a particular time (or a

particular place), and each event is independent of the others, then

the result is a poisson distribution.   this is roughly true for the

chocolate chips; one chip being in a cookie has only a small effect on

the probability that another chip will be in the cookie.

once you know you have a poisson distribution, you know a lot.   there

is only one parameter to a poisson distribution, so if you know the

mean, you know everything.   the form of the distribution is

  probability of n chips = {[e^(-x)]*(x^n)} / (n! )

the answer would be c:   ax + b = ax + c

step-by-step explanation: