# Hypothesis testing 1 poplulation mean

• Mar 21st 2009, 06:22 PM
steffan_09
Hypothesis testing 1 poplulation mean
Hi im new here so
I am getting trouble with this question, here it is:

An advertisement for a certain model of mobled phones promised that it allowed '3.5 hours talk time'.A random sample of 8 phones of this type was tested of talk time, x hours, available were as follows:

3.4,3.7,3.1,3.2,3.6,3.5,3.3,3.4
{sum of x=27.2, sum of x sqrd = 92.76}

Carry out a test, at the 5% significance level, to examine whether the advertisement was overstating the length of talk time available from the phone.

"I got Ps= 3.4 so how do you get Q, i know that Q=1-P, but you will get a -ve!
Thanks
• Mar 21st 2009, 08:01 PM
matheagle
I'm not sure what you mean by p and q.
This seems to be a straightforward one sample t-test.

You want to prove $\displaystyle H_a: \mu< 3.5$ and by default $\displaystyle H_0: \mu= 3.5$.

Get $\displaystyle \bar X$ and $\displaystyle S^2$.

Your test stat is $\displaystyle {\bar X-3.5\over S/\sqrt{n}}$

and your rejection region is $\displaystyle (-\infty, -t_{n-1,\alpha})$.
• Mar 22nd 2009, 04:21 AM
steffan_09
Ans
• Mar 22nd 2009, 06:39 AM
matheagle
I didn't check your math.
But one error is your $\displaystyle \mu$'s.
There's only one mean, so under $\displaystyle H_a$ it's just $\displaystyle \mu$ and not $\displaystyle \mu_1$.