Mike and his friends bought cheese wafers for $2 per packet and chocolate wafers for $1 per packet at a carnival. they spent a total of $25 to buy a total of 20 packets of wafers of the two varieties.

part a: write a system of equations that can be solved to find the number of packets of cheese wafers and the number of packets of chocolate wafers that mike and his friends bought at the carnival. define the variables used in the equations.
part b: how many packets of chocolate wafers and cheese wafers did they buy? explain how you got the answer and why you selected a particular method to get the answer.

Atest of sobriety involves measuring the subject's motor skills. a sample of 31 randomly selected sober subjects take the test and produce a mean score of 64.4 with a standard deviation of 2. a claim is made that the true mean score for all sober subjects is equal to 65. for each part below, enter only a numeric value in the answer box. for example, do not type "z =" or "t =" before your answers. round each of your answers to 3 places after the decimal point. (a) calculate the value of the test statistic used in this test. test statistic's value = (b) use your calculator to find the p-value of this test. p-value = (c) use your calculator to find the critical value(s) used to test this claim at the 0.2 significance level. if there are two critical values, then list them both with a comma between them. critical value(s) =