Question

A subscriber is allowed to make a certain number of telephone calls for a total charge of usd 300. Beyond that, he is charged at a certain rate per call. Two subscribers together make 1400 calls, and were charged usd 425 and usd 925 respectively. If a single person had made all of the 1400 calls he would have been charged usd 1550. How many telephone calls are allowed for the first usd 300?

Answer 1

The options for this question are missing. Here are the missing options:

a)300  

b) 350  

c) 400

d) 450

Answer:

Let x call can be made through Rs 300

each call cost=(1550-300)/(1400-x)=1250/(1400-x) - (this will be an equation 1)

We know that 1400 call made by two subscriber

1st Subscriber:

Rs 300 for x calls and Rs 125 for remaining calls

2nd Subscriber:

Rs 300 for x calls and Rs 625 for remaining calls

remaining calls = 1400-2x

Each call cost= (Rs 125 (Ist subscriber) + 625 (2nd subscriber))/(1400-2x)

(750)/(1400-2x) (this will be an equation 2)

So when we solve both equations we will get 400

So the final answer for this question is Option C) 400

If there is any confusion please leave a comment below.