Statistics and Probability Answers

determined that
children under 2 years old who sleep with the light on have a 36 % chance of becoming myopic
before they are 16. Children who sleep in darkness have a 21 % chance of becoming myopic. A
survey indicated that 28% of children under 2 sleeps with some light on. Find the probability
that child under 16 is myopic.

The employment status of working students in Urdaneta City is below. Is there any difference in the proportion of employed in males and females? At 0.05 level of significance.
GENDER
EMPLOYMENT STATUS

EMPLOYED
UNEMPLOYED

MALES
280
25

FEMALES
250
77

TOTAL
530
102

1. Mr. Canu and Emm administered their researcher to measure the mathematical ability of male students on some solid figures. They randomly took 10 males of Science High. Their scores in each solid figures are shown below. Use 0.05 level of significance
Student
1
2
3
4
5
6
7
8
9
10

Cube
10
7
5
5
4
3
7
3
5
8

Cylinder
5
7
7
6
6
5
6
4
5
8

Access time to a supercomputer mainframe is normally distributed with an average (mean) of 92 minutes a day with a standard deviation of 11 minutes. Find the probability that on access time is

a).less than 60 minutes.



b).more than 100 minutes





c).between 70 and 90 minutes.



d).between 1 and 2 hours.



e). On 15% of the days, the access time is more than how many minutes?

At the beginning of school year the average reading comprehension of freshmen college students was recorded at 79.40. After 3 months of studying the same instruments for reading comprehension test was used for 56 students and scored an average of 86.48 with a standard deviation of 4.65. Does staying in the college improve reading comprehension of the freshmen students? Use 0.05 level of significance

The average length of time for students to register in the 1st semester at a certain school has been 50mins. A new registration procedure is being tested. If random samples of 20 students have an average of 45mins with a standard deviation of 9mins under the system, can you conclude that the new system is faster than the old? Use 0.01 level of significance.

The weight of students ina college has a mean of 40kgs and standard dev of 5 kg.In a random sample of 5 students what is the probability that
1) all have weight>50kg
2) 3 will have weight>50kg

500 students selected at random from 1500 students enrolled in a computer crash
programme were classified according to the age and grade points giving the
following data:
Age (in years)
Grade Point Below 20 21-30 Above 30
Up to 5 30 50 20
5.1 to 7.5 80 70 50
7.6 to 10.0 40 80 80

Test at 5% level of significance that age and grade points are independent

The operations manager of a package delivery service is contemplating the purchase of a new fleet of trucks. When packages are efficiently stored in the truck for delivery, there are two major constraints that have to be considered - the weight (in pounds) and the volume (in cubic feet) for each item. Management takes a sample of 200 packages. The average weight is 26.0 pounds with a standard deviation of 3.9 pounds. The average volume for each package is 8.8 cubic feet with a standard deviation of 2.2 cubic feet Management is concerned with the variability of both the weight and volume. Management wants you to determine does the weight or volume have greater variability? Prove statistically

Smaller interval sizes always allow you to get a smoother polygon that will better represent the data.

True
False

The interval size is chosen when the difference between the polygon and the histogram bars is as small as possible.

True
False

The interval size does not depend on the number of data points.

True
False