You are to take a multiple-choice exam consisting of 64 questions with two possible responses to each question. Suppose that you have not studied and so must guess (select one of the two answers in a completely random fashion) on each question. Let x represent the number of correct responses on the test.(a) What kind of probability distribution does x haveb) Compare the variance and standard deviation of x.

x has a binomial distribution. The variance of x is 16 and the standard deviation is 4.

Step-by-step explanation:

For each question, there are only two possible outcomes. Either the person answer it correctly, or the person answers it wrong. The probability of answering a question correctly is independent of other questions. So we use the binomial probability distribution to solve this question.

Binomial probability distribution

Probability of exactly x sucesses on n repeated trials, with p probability.

The variance of the binomial distribution is:

The standard deviation of the binomial distribution is:

a) What kind of probability distribution does x haveb) Compare the variance and standard deviation of x.

Binomial

64 questions, so

Each question is guessed, out of two possible answers. So

x has a binomial distribution. The variance of x is 16 and the standard deviation is 4.

The jar contains 156 grams of zinc

Step-by-step explanation:

Ratios

Let's call

Z=gr of zinc

C=gr of copper

We know the ratio between them in a certain chemical is:

The jar of the chemical contains C=663 gr of copper. Calculate the grams of zinc by solving the above relation for Z:

Multiplying by C:

Substituting the value of C:

Z=156 gr

The jar contains 156 grams of zinc