Search & Filtering
The annual wages X of the staffs of collage of natural sciences are normally
distributed with mean µ and standard deviation σ. Knowing that P(X > 42320) =
0.0853 and P(X < 41230) = 0.6103, find µ and σ.
Suppose that an examination consists of six true and false questions, and assume that
a student has no knowledge of the subject matter. The probability that the student will
guess the correct answer to the first question is 30%. Likewise, the probability of
guessing each of the remaining questions correctly is also 30%.
a. What is the probability of getting more than three correct answers?
b. What is the probability of getting at least two correct answers?
c. What is the probability of getting at most three correct answers?
d. What is the probability of getting less than five correct answers
A ball is drawn at random from an urn containing one red and one white ball. If the
white ball is drawn, it is put back into the urn. If the red ball is drawn, it is returned to
the urn together with two more red balls. Then a second draw is made. What is the
probability a red ball was drawn on both the first and the second draws?
A box of 80 candles consists of 30 defective and 50 non defective candles. If 10 of
this candles are selected at random by business man for sale, what is the probability
a. All will be defective
b. 6 will be non-defective
c. All will be non-defective
Two dice are rolled. Let X be a random variable denoting the sum of the numbers on
the two dice.
i) Give the probability distribution of X
ii) Compute the expected value of X and its variance
Among 15 clocks there are two defectives. In how many ways can an inspector chose
three of the clocks for inspection so that:
a. There is no restriction.
b. None of the defective clock is included.
c. Only one of the defective clocks is included.
d. Two of the defective clock is included.
A package contains 12 resistors, 3 of which are defective. If 3 are selected, find the probability of getting
(a) no defective resistor.
(b) one defective resistor.
(c) all defective resistors
a) Determine the missing frequencies of the following distribution given that the median
is 33.5 and themode is 34.0.
Class limits 0-9 10-19 20-29 30-39 40-49 50-59 60-69 Total
Freq. 4 16 f3 f4 f5 6 4 230
b) Compute the arithmetic mean.
c) Compute the value below which 25% of the observations lie.
d) Compute the value above which 25% of the observations lie
Find 90% confidence interval for the mean of normal distribution if a sample of size 7 gave the values 9,16,10,14,8,13,14
Keith’s Florists has 15 delivery trucks, used mainly to deliver flowers and flower arrangements in the Greenville, South Carolina, area. Of these 15 trucks, 6 have
brake problems. A sample of five trucks is randomly selected. What is the probability that two of those tested have defective brakes?
