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# normal distribution question watch

1. a teacher travels from home by car each weekday. her journey times are normally distributed with a mean of 30.4 mins and a standard deviation of 3.6 mins. calculate the probability that her journey time on a particular day takes between 25 minutes and 35 minutes.

ive standardised and got p(-1.5<z<1.28), where do i go next?
2. (Original post by shubhondeb)
a teacher travels from home by car each weekday. her journey times are normally distributed with a mean of 30.4 mins and a standard deviation of 3.6 mins. calculate the probability that her journey time on a particular day takes between 25 minutes and 35 minutes.

ive standardised and got p(-1.5<z<1.28), where do i go next?
Draw a bell curve and consider the region you need to find.

Are you doing old (modular) spec or new spec? The method you use depends on this.
3. To find the relevant area of the Normal Distribution note:

using tables to find P(a) and P(a).

Also do you know how to deal with "P(a)" where a is negative?

Spoiler:
Show

P(-n) = 1 - P(n), where "-n" is a negative value (using symmetry).

Can you take it forward from here?
4. (Original post by Notnek)
Draw a bell curve and consider the region you need to find.

Are you doing old (modular) spec or new spec? The method you use depends on this.
old spec s1
5. (Original post by simon0)
using tables to find P(a) and )(a).

Can you take it forward from here?
Ah i see, thank you!

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