1. ## Algebra

Call - me

Monthly rental 12 pounds
Calls only 2p per minute

Acme Telecom

No rental
No standing charge
Just 5p per minute
____________________________________

You are thinking of changing your phone company and you see the above offers. Deciding which company is making the best offer depends on the total length of calls you are likely to make each month.

(a) The total number of minutes your calls last each month is m
Write down an expression for the total cost, in pence, if you go for

(i) 'call - me'
(ii) Acme Telecom

(b) Use your expressions to form an equation so that you can find the value of m for which the companies charge the same amount. Solve teh equation to find the value of m.

(c) By considering what happens if m is lower and if m is higher than the value you have just worked out, explain how you would choose your telephone company.

2. Originally Posted by Ponda
Call - me

Monthly rental 12 pounds
Calls only 2p per minute

Acme Telecom

No rental
No standing charge
Just 5p per minute
____________________________________

You are thinking of changing your phone company and you see the above offers. Deciding which company is making the best offer depends on the total length of calls you are likely to make each month.

(a) The total number of minutes your calls last each month is m
Write down an expression for the total cost, in pence, if you go for

(i) 'call - me'
(ii) Acme Telecom

(b) Use your expressions to form an equation so that you can find the value of m for which the companies charge the same amount. Solve teh equation to find the value of m.

(c) By considering what happens if m is lower and if m is higher than the value you have just worked out, explain how you would choose your telephone company.
Let c be the cost with respect of the time m (in minutes). Note that ₤12 = 1200 p

a) (i) $\displaystyle c(m) = 1200 + 2m$
a) (ii) $\displaystyle c(m) = 5m$

b) Solve the equation for m:

$\displaystyle 1200+2m = 5m$. I've got m = 400

c) If m < 400 then you pay less with Acme and if m > 400 then Call-me is cheaper.