Homework Answers

According to a study conducted by grade 11 students, Php155 is the monthly expense for cellphone loads of high school students on their province. A statistics students claims that this amount has increased since January of this year. Do you think his claim is acceptable if a random sample of 50 students has an average monthly expense of Php165 on cellphone loads? Using 0.05 level of significance, assume that a population standard deviation of Php52.

"\\begin{Bmatrix}\n a \\\\\n b\n\\end{Bmatrix} = 1\/314*\\begin{bmatrix}\n 198 & -26 \\\\\n -26 & 5\n\\end{bmatrix}\\begin{Bmatrix}\n 1230 \\\\\n 6950\n\\end{Bmatrix}"

X= 38; n= 100 - find p =

X= 55; n= 240 - find p=

X= 38; n= 100 find p=

2. The average length of time for students to

have their subjects controlled is 40 minutes. A

new controlling procedure using modern

computing machines is being tried. If a random

sample of 15 students has an average

controlling time of 25 minutes with a standard

deviation of 12.9 minutes under the new

system, test the hypothesis that the average

length of time to control student’s subjects is

less than 40 minutes. Use a level of

significance of 0.10 and assume the

population of controlling times to be normally

distributed.

1. The probability distribution below shows the number of typing errors (x) and the probability p(x) of committing these errors whenever clerks type-in a document. Compute the variance and standard deviation.

y

1

2

3

4

5

P(y)

0.02

0.11

0.42

0.31

0.10

0.04

2. The probability distribution below shows the random variable and the probability of tossing a die. What is the variance and standard deviation?

z

1

2

3

4

5

6

P(z)

1/6

1/6

1/6

1/6

1/6

1/6

must include solution