Math Is Fun Forum

i am at a loss. Please Help

1.Many companies test prospective employees for drug use. Suppose a company uses a test that is 98% accurate – that is it correctly identifies an applicant as a user or nonuser with probability .98. The test is performed on each applicant twice and the outcomes are independent.
a) Use a tree diagram to sketch this two stage experiment.

b) Find the probability that a nonuser fails both tests.

c) Find the probability that a user fails at least one test.

d) Find the probability that a user passes both tests.

2. Two representatives are randomly selected from a list of six people, 4 male, 2 females. Let the random variable X represent the number of females selected.

a) Construct a probability distribution table for the random variable X.

b) What is the probability that there will be at least one female representative?

c) What is the probability that there will at most one female representative?

d) Calculate the mean and standard deviation for the random variable X.

Hi,

I'm having trouble understanding the Monthly payment formula such as (P x (i / 12)) / (1 - (1 + i / 12)-n).

For example, when I try to calculate the monthly p on a 25,000 loan, with a 6% interest rate and a term of 36 months. I multiply 25,000 x 0.005 which gives 125. Then, I add 1 + 0.005 = 1.005 and raise that to -36 power, which gives 0.84. Then I subtract 1 and that gives -0.16. Then I divide 125 by the -0.16 and the answer comes to -781.25.

I know that the answer should be 760.55, so what am I doing wrong?

Please break it down completely and provide each step with this example. Also, please provide some other examples with different loan amounts, interest rates, and months so I can understand better.

Thanks!

1.determine whether or not the given procedure results in a binomial distribution. For those that are not bi-nomial, identify at least one requirement that is not satisfied.Treating 152 couples with the YSORT gender selection method devel-oped by the Genetics & IVF Institute and recording the gender of each of the 152 babies that are born.

10. Assume that a procedure yields a binomial distribution with n trials and the probability of success for one trial is p. Use the given values of n and p to find the mean and standard devi-ation Also, use the range rule of thumb to find the minimum usual value. The final exam in a sociology course consists of 100 multiple- choice questions. Each question has 5 possible answers, and only 1 of them is correct. An unprepared student makes random guesses for all of the answers.

1.    Finding Probability from Odds If the actual odds against event A are a: b,  P( A) = b/( a + b).
then Find the probability of the horse Cause to Believe winning the 132nd Kentucky Derby, given that the actual odds against his winning that race were 97: 3.

2.    Are these events disjoint? Randomly selecting a fruit fly with red eyes Randomly selecting a fruit fly with sepian ( dark brown) eyes.
3.    If events A and B are disjoint and events B and C are disjoint, must events A and C be disjoint? Give an example supporting your answer.
4.    Are these events dependent? Finding that your cell phone works Finding that your car starts
5.    The FICO ( Fair Isaac & Company) score is commonly used as a credit rat-ing. There is a 1% delinquency rate among consumers who have a FICO score above 800. If four consumers with FICO scores above 800 are randomly selected, find the probability that at least one of them becomes delinquent.
6.    How many ways can the letters of Baggy be arranged?

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can be made?

What is the probability that if a couple plans to have 10 children what is the probability that there will be at least 1 girl?