Math question from last year's released sat practice test??

Test Preparation SAT Preparation
1

<p>Can anyone explain this question (its from the preparation booklet for 2007-2008)</p>

<p>A telephone company charges x cents for the first
minute of a call and charges for any additional time
at the rate of y cents per minute. If a certain call
costs $5.55 and lasts more than 1 minute, which of
the following expressions represents the length of
that call, in minutes?
(A) 555 - x/y
(B)555 + x - y/y
(C)555 - x + y/y
(D)555 - x - y/y
(E) 555/ (x + y)</p>

<p>It says the answer is C but I dont get why..I mean if the first minute costs x and u subtract that from 555 arent you going to calculate the minutes 1 less than what they should be..im confused!</p>

2

<p>what the heck means 555 - x +y/y ,is it 5.55 - (x+y)/y ???</p>

3

<p>because the x and y are in cents so the dollars must be converted into cents</p>

4

<p>thats a plug in question for sure... let x=55cents then y=50c you should get 11 minutes... just plug those values into each of the answers and you should find the one you need</p>

<p>C is (555-x+y)/y because you need to find the length of the call in minutes you know they charge x for the first minute but if you minus x from 555 and then divide by y your missing the first minute. so you need to add a minute onto 555 - x and since they charge y cents for that minute you add that as a way of adding a minute. does that make sense?</p>

5

<p>If the rate for the whole call were y cents per minute then the length of the call would be 555/y minutes.
In reality you spend x cents for the first minute and 555-x cents for the remaining (555-x)/y minutes, so the total length of the call is
1 + (555-x)/y =
y/y + (555-x)/y =
(555-x+y)/y.</p>

6

<p>The length after the first minute is (555-x)y
Before this,there is the first minute
so 1 + (555-x)/y = answer E,after simplifying.</p>

7

<p>but hold on how is ((y/y)/y) equal to y/y-i guess i jus dont know the rules-it always confuses me!-plz clarify</p>

8

<p>y/y and (555-x)/y are two separate fractions. I hope it answers your question.</p>

9

<p>you can just make it much simpler for yourself..
say that x = 3 cents and y = 4 cents
Say that you speak for 3 minutes.. that would mean that the call would cost 3 cents (first minute) plus 4*2(number of minutes after the first call), giving you a total of 11 cents for the call</p>

<p>then you can just replace 11 with 555 in each equation and test each equation..
you will see that C works</p>

10

<p>x(1st minute)+y(total minutes- 1st minute)= 555 cents
1x + y(t.m)-y(1)= 555 cents</p>

<p>Solve for total minutes(t.m)</p>

<p>(555-1x+1y)
---------- = t.m<br>
y</p>