Statistics
posted by Edward .
A set of telephone lines is to be installed so as to connect between town A and town B. The town A has 2000 telephones. If each of the telephone users of A were to be guaranteed instant access to make calls to B, 2000 telephone lines would be needed. This would be rather extravagant. Suppose that during the busiest hour of the day, each supscriber in A requires, on the average, a telephone connection to B for two minutes, and that these telephone calls are made at random. Find the minimum number M of telephone lines to B which must be installed so that at most, only 1% of the callers of town A will fail to have immediate access to a telephone line to B. (Suggestion!: approximate the distribution by a Gaussian distribution to facilitate the arithmetic)"

This question was posted twice in a row. I may look at it later, if someone else doesn't do it first.

Yes please. I think I hit the refresh button while posting. Sorry. Would love to work with you on getting some hints on getting this done.

If I'm interpreting this problem correctly and since the suggestion is to approximate the distribution by using the Gaussian (or normal) distribution, I would first find the zscore equated to 1% using a ztable. That would be 2.33 (below the mean of the distribution). Next, you will need to find mean and standard deviation. Once you have those values, substitute into the zscore formula, then solve for x.
Mean = np = (2000)(.5) = ?
Standard deviation = √npq = √(2000)(.5)(.5) = ?
Note: I am using .5 since no value for p is stated. Also, q = 1  p.
Formula for zscore:
z = (x  mean)/sd
Substitute the values for mean and standard deviation when you finish the above calculations:
2.33 = (x  mean)/sd
Now solve for x.
I hope this will help and is what the problem was asking.
Respond to this Question
Similar Questions

math (unanswered, previously posted)
A set of telephone lines is to be installed so as to connect between town A and town B. The town A has 2000 telephones. If each of the telephone users of A were to be guaranteed instant access to make calls to B, 2000 telephone lines … 
math
One day we decided to drive from Town A to Town D. In order to get there we had to drive through Town B and then Town C. It is 10 miles farther from Town A to Town B than it is from Town B to C. IT is 10 miles farther from Town B to … 
geometry
On a map, Town A is 8 km due south of Town B, Town C is 9 km from Town A, and Town C is 3 km from Town B (see figure below). Find the bearing from Town A to Town C and the bearing from Town B to Town C. 
Math
A motorist took a total of 4hr to drive from town A to town C. He took 1hr to travel from town A to town B,which is between town A & town C. The distance between town B & town C is 11/15 of the distance between town A and town C. If … 
Math
One day we decided to dive from town A to town B. In order to get there we had to drive through town B and then town C. it is 10 miles farther from town A to town B then it is to town B to C. It is 10 miles farther from town B to town … 
Math
One day we decidid to drive from town A to town D.In order to get there,we had to drive through town B and C.It is ten miles farther from town A to town B than it is from town B to town C.It is ten miles farther from town B to town … 
math
Town P is on bearing 315 degree from town Q. While town R is south of town P and west of town Q. If town R is 60km away from Q, how fara is R from P? 
Math
Predicted winner in an election for town mayor . Method C: Telephone 100 randomlychosen voters who live in the town. 54 percent plan to vote for the incumbent mayor. Method D: Telephone 70 people who have lived in the town for more … 
statistics
suppose a car is driven from town A to town B from town B to town C and from town C to town D which have equal distances at average speeds 20km/hr,60km/hr and 120km/hr respectively,what is the average speed for the whole journey 
Math
An aeroplane travelling from town A to town C travels 9km due west to Town B and then 12km due south to town C. Sketch a diagram to represent the movement of the diagram from Town A to Town C Calculate the distance between Town A and …