The proportion of students who own a cell phone on college campuses across the country has increased tremendously over the past few years. It is estimated that approximately 90% of students now own a cell phone. Fifteen students are to be selected at random from a large university. Assume that the proportion of students who own a cell phone at this university is the same as nationwide. Let X = the number of students in the sample of 15 who own a cell phone. 1. What is the appropriate distribution forX? **N = Normal, B = Binomial?
A. X is M(15, 0.9).
B, X is B(15, 09).
C. Xis B(15, 13.5).
D. Xis N(13,5, 1.16).
2. On average, how many students will own a cell phone in a simple random sample of 15 students?
a. 9.
b. 13
c. 13.5.
d. 14 17.
3. What is the standard deviation of the number of students who own a cell phone in a simple random sample of 15 students?
a. 0.077.
b. 0.09.
c. 1.16.
d. 1.35.
4. What is the probability that all students in a simple random sample of 15 students own a cell phone?
a. 0.
b. 0.1.
c. 0.206.
d. 0.9.

Complete Question

The complete question is shown on the uploaded image  

1 ) The correct option B

2) The correct option is  C

3)  The correct option is  C

4)  The correct option is  C

Step-by-step explanation:

From the question we are told that

   The proportion that own a cell phone  is  

    The  sample  size is  n =  15

Generally the appropriate distribution for X is mathematically  represented as

So  

Generally the number students that  own a cell phone in a simple random sample of 15 students is mathematically represented as

Generally the standard deviation of the number of students who own a cell phone in a simple random sample of 15 students is mathematically represented as

Where  q is mathematically evaluated as

Generally the probability that all students in a simple random sample of 15 students own a cell phone is mathematically represented as

From the combination calculator  is      

answer: hey there,

the answer you are looking for is a..

hope this you!

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18