An ACNielsen study indicates that mobile subscribers between 18 and 24 years of age spend a substantial amount of time watching video on their devices, reporting a mean of 325 minutes per month. Assume that the amount of time spent watching video on a mobile device per month is
normally distributed and that the standard deviation is 50 minutes.
a. What is the probability that an 18- to 24-year-old mobile subscriber spends less than 300 minutes watching video on his or her mobile device in a given month?
b. What is the probability that, for 2 randomly selected 18- to 24-year-old mobile subscribers, both spent less than 300 minutes watching video on their mobile device in a given month?
c. What is the probability that, for 2 randomly selected 18- to 24-year-old mobile subscribers, the sum of time they spent watching video on their mobile device in a given month is less than 600 minutes?
d. What is the number of minutes such that 25% of all 18- to 24-year-old mobile subscribers will spend less than that number of minutes watching video on his or her mobile device per month?
A survey asked teens in the seventh through twelfth grade to estimate the likelihood that they would be married within ten years. The responses are tabulated below.
Female | Male | Total | |
Less than 50% | 502 | 522 | 1024 |
At least 50% | 2154 | 1699 | 3853 |
Total | 2656 | 2221 | 4877 |
What is the probability that a randomly selected study participant believes that the probability that he or she will be married within ten years is less than 50%? Round your answer to four decimal places.
Oasis is an asset management company in South Africa. It has found that there is a three-in-five chance that a general equity unit trust fund will perform better than the overall JSE share index over any one-year period. Seven general equity unit trust funds are randomly selected from general equity unit trust funds. What is the probability that at most two of these general equity trust funds performed better than the overall JSE share index over the past year (rounded off to three decimals)?
Carry your intermediate computations to at least four decimal places. Round your answer to at least three decimal places.
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Suppose it is known that the distribution of purchase amounts by customers entering a popular retail store is approximately normal with mean $75 and standard deviation $20. A. What is the probability that a randomly selected customer spends more than $45 at this store? B.Find the dollar amount such that 75% of all customers spend no more than this amount. C. Find the dollar amount such that 80% of all customers spend at least this amount. D. Find two dollar amounts, equidistant from the mean, such that 90% of all customer purchases are between these values. |
7.) According to a study done by Nick Wilson of Otago University Wellington, the probability a randomly selected individual will not cover his or her mouth when sneezing is 0.267. Suppose you sit on a bench in a mall and observe people’s habits as they sneeze.
(a) What is the probability that among 10 randomly observed individuals, exactly 4 do not cover their mouth when sneezing?
(b) What is the probability that among 10 randomly observed individuals, fewer than 3 do not cover their mouth when sneezing?
(c) Would you be surprised if, after observing 10 individuals, fewer than half covered their mouth? Why?
Find two dollar amounts, equidistant from the mean, such that 90% of all customer purchases are between these values.
The owner of a pet store is trying to decide whether to discontinue selling specialty clothes for pets. She suspects that only 10% of the customers buy specialty clothes for their pets and thinks that she might be able to replace the clothes with more interesting and profitable items on the shelves. Before making a final decision she decides to keep track of the total number of customers for a day, and whether they purchase specialty clothes for their pet.
a) What is the probability that at least 3 of the first 35 customers buy specialty clothes for their pet?
b) The owner had 275 customers that day. Assuming this was a typical day for his store, what would be the mean and standard deviation of the number of customers who buy specialty clothes for their pet each day?
(Rather solving by hand is there excel or PHStat method to use? An easy way to solve a? can you please show me how?)
A political pollster is conducting an analysis of sample results in order to make predictions on election night. Assuming a two-candidate election, if a specific candidate receives at least 55% of the vote in the sample, that candidate will be forecast as the winner of the election. You select a random sample of 100 voters. Complete parts (a) through (c) below.
What is the probability that a candidate will be forecast as the winner when the population percentage of her vote is 50.1%? |
A machine is made up of 3 components: an upper part, a mid part, and a lower part. The machine is then assembled. 5% of the upper parts are defective; 4% of the mid parts are defective; 1% of the lower parts are defective. What is the probability that a machine is non-defective?
If a person visits his dentist, suppose that the probability that he will have his teeth cleaned is 0.44, the probability that he will have a cavity filled is 0.24, the probability that he will have a tooth extracted is 0.21, the probability that he will have his teeth cleaned and a cavity filled is 0.08, the probability that he will have his teeth cleaned and a tooth extracted is 0.11, the probability that he will have a cavity filled and a tooth extracted is 0.07, and the probability that he will have his teeth cleaned, a cavity filled, and a tooth extracted is 0.03. What is the probability that a person visiting his dentist will have at least one of these things done to him?
Please help solve the following problem. Please provide step by step calculations with explanations.
Given 20 people, what is the probability that among the 12 months of the year there are 3 non necessarily consecutive months containing exactly 4 birthdays?
hints:
1. to count the number of elements of the state space, look at the following proposition:
There are ( n + r -1 choose r-1 ) distinct nonnegative integer valued vectors
(x_1, x_2, … , x_3) satisfying
x_1 + x_2 + … x_r = n
hint 2:
assume that each month has the same number of days, so that the probability that a birthday falls in a particular month is 1/12.
A particular airline has 10:00 a.m. flights from San Francisco to New York, Atlanta, and Miami. The probabilities that each flight is full are 0.60, 0.40, and 0.50 respectively, and each flight is independent one another.
a) What is the probability that all flights are full?
b) What is the probability that only the New York flight is full?
c) What is the probability that exactly one flight is full?
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