Turn on thread page Beta
    • Thread Starter

    A group of students believes that the time taken to travel to college, T minutes can be assumed to be normally distributed. Within the college 5% of students take at least 55 minutes to travel to college and 0.1% takes less than 10 minutes. Find the mean and standard deviation of T..
    •  Official Rep

     Official Rep
    Sorry you've not had any responses about this. Are you sure you've posted in the right place? Here's a link to our subject forum which should help get you more responses if you post there.

    Just quoting in Fox Corner so she can move the thread if needed :wizard:
    (Original post by Fox Corner)

    (Original post by sunshinewothaya)
    Within the college 5% of students take at least 55 minutes to travel to college
    In other words, P(T >= 55) = 0.05. Which can be rephrased as P(T < 55) = 0.95.

    0.1% takes less than 10 minutes.
    and P(T < 10) = 0.001.

    Recall that z = \dfrac{x-\mu}{\sigma}. You can find z with the probabilities above, your x's are 55 and 10, and the formula I gave will let you use this data to construct a pair of simultaneous equations which will yield the mean and standard deviation.
The home of Results and Clearing


people online now


students helped last year

University open days

  1. Bournemouth University
    Clearing Open Day Undergraduate
    Wed, 22 Aug '18
  2. University of Buckingham
    Postgraduate Open Evening Postgraduate
    Thu, 23 Aug '18
  3. University of Glasgow
    All Subjects Undergraduate
    Tue, 28 Aug '18
How are you feeling about GCSE results day?
Useful resources

Make your revision easier


Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here


How to use LaTex

Writing equations the easy way

Student revising

Study habits of A* students

Top tips from students who have already aced their exams

Study Planner

Create your own Study Planner

Never miss a deadline again

Polling station sign

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.