Thread: Mobile Phone rate plans - HELP!

Imagine.. A $50 mobile phone plan.

Mobile calls 10c per 30 seconds.
Land Line calls 29c per 30 seconds.

A customer states "30% of my calls are to mobiles, the other 70% are to landlines, how many hours of talk time (in decimal) do I get for mobile calls and landline calls?"

I need an equation for this to which I could apply if the percentages changed to say 15% and 85%.

Thanks guys

Psylencer.

By the way I need a response I can understand...Im no maths genius. Thanks

Hello, psylencer!

Not to worry . . . Baby-talk is my specialty.

Imagine.. A $50 mobile phone plan.

Mobile calls: 10¢ per 30 seconds.
Land Line calls: 29¢ per 30 seconds.

A customer states "30% of my calls are to mobiles, the other 70% are to landlines.
How many hours of talk time (in decimal) do I get for mobile calls and landline calls?"

I need an equation for this to which I could apply if the percentages changed to, say, 15% and 85%.

Let's solve this particular problem first . . . then we'll generalize it.

Let = total talk time (in hours).

The rates are:

Since 30% of the calls are Mobile, he talks hours at $12/hour.
. . His mobile calls cost him: dollars.

Since 70% of the calls are Landline, he talks hours at $38.40/hour.
. . His landline calls cost him: dollars.

His total cost will be $50: .

Solve for

For his $50, he can talk a total of:

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Now, we'll generalize the problem,
. . keeping the hourly rates constant.

Let = percent of T used on Mobile calls.
. . Time on mobile calls: hours.
Then mobile calls cost: dollars.


Then = percent of T used on Landline calls.
. . Time on landline calls: hours.
Then landline calls cost: dollars.

The total cost is $50, so: .

Solve for and we get: .

Thanks Soroban,

I got the first part, but not the last part. As you can probably tell, Im interested in maths (not a student) but no good at it. Any chance we could go back a step? I still dont see how the percentages work. HOLD ON!...I GOT IT..HAHA! Dont worry Thanks heaps. You guys are brilliant.



Thanks
Psylencer