# Combinatorics - math problems

#### Number of problems found: 408

- Population variance

In a California community college, 60% of students will transfer to a college in the CSU system. The number of students in a sample who will transfer follows a binomial distribution. If 8 students are randomly selected, find the population variance σ^{2}of - Sample Proportion

In a California community college, 60% of students will transfer to a college in the CSU system. The number of students in a sample who will transfer follows a binomial distribution. 400 students are randomly selected from the college and 224 of them will - Suppose 4

Suppose that 14% of all steel shafts produced by a certain process are nonconforming but can be reworked (rather than having to be scrapped). Consider a random sample of 200 shafts, and let X denote the number among these that are nonconforming and can be - Rich retirement

Health care issues are receiving much attention in both academic and political arenas. A sociologist recently conducted a survey of citizens over 60 years of age whose net worth is too high to qualify for government health care but who have no private hea - The flag

The flag should consist of 3 different colored stripes. Available colors: white, red, blue, green and yellow. Specify: A) number of all flags B) number of flags with a blue stripe C) number of flags with a blue stripe in the middle D) the number of flags - The vaccination

The vaccination coverage of the population is 80%. Unvaccinated make up 60% of all infected. What percentage are unvaccinated more likely to be infected? - Mortality tables

Mortality tables enable actuaries to obtain the probability that a person at any age will live a specified number of years. Insurance companies and others use such probabilities to determine life-insurance premiums, retirement pensions, and annuity paymen - An aircraft

An aircraft manufacturing company has submitted bids on two separate airline contracts, A and B. The company feels that it has a 70% chance of winning contract A and a 25% chance of winning contract B. Furthermore, it believes that winning contract A is i - Binomial probability

What is the binominal probability that at least 4 of the 6 trials (n=6) are succeeded where φ = 0.50? - Covid-19 spread

A Street has 13 houses in a row. Some resident sin the first house tested positive for Covid-19. The virus spreads in 2 ways: It can spread to the next house or jump directly to the third house. Residents of house 2 can get infected in only one way, house - Dice 7

A standard number cube is tossed 210 times. What is a reasonable prediction for the number of times the number cube will land on a 5? - What fraction

What fraction of number 1 to 30 is prime? - And-or probabilities

P(A ) = 0.53, P(B) = 0.15, and P(A n B ) = 0.18. Find P(A U B ). Round approximations to two decimal places. - The spinner

The spinner below is spun 12 times. It landed on I 4 times, II 7 times, and III 1 time. What is the difference between the experimental and theoretical probabilities of landing on the II? - Five number code

I have a 5 digit code on the bag that I forgot. All I remember is that it was a symmetric number and the sum of its digits was 22. Write all the numbers that can be a code. . - Smoker male

For a person selected randomly from a certain population, events A and B are defined as follows. A = event the person is male B = event the person is a smoker. For this particular population, it is found that P(A ) = 0.53, P(B) = 0.15, and P(A n B ) = 0.1 - Chess pieces

There are 5 black chess pieces in the box. How many white pieces should we add to this box so that the probability of pulling out a black piece is 1: 4? - Right key

The hostel has 4 rooms. The keys to each room are not numbered. Each of the four guests took one key. What is the probability that everyone took the right key? - Poisson distribution - daisies

The meadow behind FLD was divided into 100 equally large parts. Subsequently, it was found that there were no daisies in ten of these parts. Estimate the total number of daisies in the meadow. Assume that daisies are randomly distributed in the meadow. - In PE

In PE, students play a game where they do different exercises depending on the color of marble that Coach Forbes draws. Coach Forbes has a jar with 6 red marbles, 12 blue marbles, 16 purple marbles, 2 green marbles, and 4 yellow marbles. What is the proba

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