he cost of hiring a plumber from Joe’s Plumbing Service is figured at $75 for the house call, and $40 for each?
The cost of hiring a plumber from Joe’s Plumbing Service is figured at $75 for the house call, and $40 for each hour or fraction of an hour the plumber is there. Which of the following expresses the cost c of a service call lasting t hours?
a. c(t)= 75 +40t which is what I had thought it was but I got it wrong
b. t(c) = 75t +40
c. c(t) = 115 if t is greater than or equal to 0 and smaller than or equal to 1
155 if t is greater than to 1 or smaller than or equal to 2
195 if t is greater than 2 or smaller than or equal to 3
d. all the above
I'm really sorry! I had thought I was right...in fact I still don't understand why I'm not. Thanks in advance for anyone who answers because I'm not a high enough level and stuff Thans!
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as you said:
c(t)= 75 +40t
however that is only correct in whole hours
for example:
if the number of hours was 4.5 hours which is a fraction of an hour, the cost wouldn't be:
75+40(4.5)=$255
because 4.5 hours is 4 hours and a fraction of the fifth hour so the answer would actually be:
75+40(5)=$275
so the answer would actually be c because the equation specifies about the fraction of the hours
It's not a because you have to account for the "or fraction of an hour". So it's $115 even if the call is only 5 minutes because there's a $40 charge for that 5 minutes. And as soon as it goes past 1 hour to any fraction, another $40 is added.
Option c captures that best, but doesn't cover what happens past 3 hours correctly. There are better ways to express it, but of the choices you're given, that one is closest.