Statistics and Probability Answers

The number of violent crimes committed in a day possesses a distribution with a mean of 2.8 crimes per day and a standard deviation of 4 crimes per day. A random sample of 100 days was observed, and the sample mean number of crimes for the sample was calculated. Describe the sampling distribution of the sample means.

a.) shape unknown with mean of 2.8 and a standard deviation of 0.4

b.) approximately normal with mean of 2.8 and standard deviation of 4

c.) shape unknown with mean of 2.8 and standard deviation of 4

d.) approximately normal with mean of 2.8 and standard deviation of 0.4.

Which one of the following charts represents a probability distribution?

a)

X | P(x)

 0 | 0.1

 1 | 0.2

 2 | 0.4

 3 |  0.1

b)

 X | P(x)

 0 | 0.3

 1 | 0.2

 2 | 0.1

 3 | 0.35

c)

 X | P(x)

 0 | -0.1

 1 | 0.1

 2 | 0.4

 3 | 0.6

d)

 X | P(x)

 0 | 0

 1 | 0

 2 | 1

 3 | 0

1) Newborn babies are more likely to be boys than girls. A random sample found that 13,173 boys were born among 25,468 newborn children. The sample proportion of boys was 0.5172. Is this sample evidence that the birth of boys is more common than the birth of girls in the entire population?

A Jar contains 24 red marbles numbered 1 to 24 and 50 blue marbles numbered 1 to 50. A marble is drawn at random from the Jar. Find the probability of the given event. Please enter reduced fractions.

a) The marble is red. P(red)=

b) The marble is odd numbered. P(odd)=

c) The marble is red or odd numbered. P(red or odd)=

d)The marble is blue or even numbered. P(blue or even)=

In a survey of 300 random households in a particular village, mother's have been asked if they used cellphone to communicate there are 76 who said YES, Use 90%, 95% and 99% confidence to estimate the proportion of all mothers who use the cellphone to communicate

Find the areas of each of the following z-scores

1. 0.50

2. 0.99

3. -2.58

4. 3.16

5. -0.52

6. -0.12

In a high school class, 35% of the students take Spanish as a foreign language, 15% take French as a foreign language, and 40% take at least one of these languages. What is the probability that a randomly chosen student takes French given that the student takes Spanish?