Statistics and Probability Answers

A bag contains three red and four black balls. A balls is drawn at random from the black what is the probability that the ball is black?

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question in photo

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question is in photo

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B=4

QUESTION 13
A roulette wheel is divided into 4 sectors of equal area numbered 1, 0, 3 and 6. Suppose the
wheel is spun twice and the random variable X is the sum from the two spins.
(a) Find the probability mass function of X. (3)
(b) Find the expected value of X, E.X/. (3)
(c) Find variance of X, V.X

The average number of claims per hour made to the State Insurance Company for
damages or losses incurred in moving is 3. What is the probability that in any given hour:
(i) Fewer than three claims will be made?
(ii) Exactly three claims will be made?
(iii) Three or more claims will be made?
(iv) More than three claims will be made?

A standardized statistics test was given to 50 females and 75 males. The females made an
average grade of 76 with a standard deviation of 6, while the males made an average grade
of 82 with a standard deviation of 8. Find a 96% confidence interval for the difference µ1
and µ2
, where µ1
the mean score of all males is and µ2
is the mean score of all females
who took this test.