Statistics and Probability Answers

A sample of n=21 observations is drawn from a normal population with m=1030 and standard deviation=200. Find each of the following:

A. P(X >1108)

B. P(X < 942)

C. P(X > 999)

You have an 8:00 a.m. class and based on your experience, you believe the amount of time it takes you to travel from your home to your seat in the classroom follows a normal distribution with mean 26 minutes and standard deviation 4 minutes.

What is the probability that on any given day, your travel time to class would be less than 20 minutes?

0.067

Correct: Your answer is correct.

What is the probability that on any given day, your travel time to class would be between 20 and 30 minutes?

0.775

Correct: Your answer is correct.

Then, you have no desire to be late to class, but neither do you want to leave the house every day at 6:00 a.m. for your 8 o'clock class. You are willing to risk being late to class 1% of the time, and the question is what is the latest time you can leave the house to have no more than a 1% probability of being late to class?

The IB grades attained by a group of students are listed as follows. 6, 4, 5, 3, 7, 3, 5, 4, 2, 5.

find the probability that a student chosen at random from the group scored at least a grade 4.

Calculate a 90% confidence interval for the average age at which gifted children first count to 10 successfully. Choose the closest answer.

2. These are the marks of 8 students: 70, 71, 73, 74, 68, 72, 71, 12 a) Calculate the mean. b) Calculate the median. c) Why are they different? 3. What percent of the class scores below each measure of central tendency? % scoring less than mean = % scoring less than the median = 4. Tamara's mark is higher than 63% of the class. a) What percentile does she fall into? b) How many students score less than she does? c) What is Tamara’s score?

Vice Ganda plans to invest 100,000 pesos for a movie block screening for a cause. He expects to sell tickets worth 150,000 pesos. But if the typhoon hits on the day of the screening, they cannot sell any tickets. If the weather forecast tells that there is a 20% possibility that there will a typhoon on the screening day, how much will he expect to gain/lose in return?