# Math Help - statistics

1. ## statistics

1. It is known from past experiences that a mean of 85 and standard deviation of 25 is found and has a normal distribution.
a. determine if this sample tends to support or refute the assumed population mean at the 10% significance level (i.e. alpha=0.10) based on using the assumed value of the population standard deviation. Find the critical value, test statistic, probability value. Create conclusion.
2. Repeat this based on the sample standard deviation....these numbers are given: 80, 60, 65, 95, 100, 90, 20, 55. I calculated mean of 70.6 and st. dev. of 26.4. No p-value needed for this one.

2. So $H_0: \mu = 85$ and $H_A: \mu \neq 85$. Calculate the t-statistic $t = \frac{\bar{x} - \mu_{0}}{s/\sqrt{n}}$. Wree you given a sample population?