Abank wishes to estimate the mean credit card balance owed by its customers. the population standard deviation is estimated to be $300. if a 98 percent confidence interval is used and an interval of $78 is desired, how many customers should be sampled? a. 725b. 80c. 57d. 320

B. 80

Step-by-step explanation:

We know that the formula to find the sample size is given by :-

, where = population standard deviation.

E= margin of error

z*= Two -tailed critical z-value

Given : Confidence level = 98% =0.98

Population standard deviation :

Also, from z-table for (two tailed ), the critical will be =

Then, the required sample size must be :

 [To the nearest option]

Hence, the required sample size = 80

Hence, the correct option is option B. 80

option 2 is correct.

step-by-step explanation:

we are given two inequality equation

x+y> 5 and -3x+2y< -2

first we draw the graph of both function using t-table method

equation: x+y> 5

for x=0, y=5

for x=-5, y=0

table:

x   :   0     5

y   :   5     0

test point (0,0) , 0> 5

false

equation: -3x+2y< -2

for x=0, y=-1

for x=2, y=4

table:

x   :   0     2

y   : -1       4

test point (0,0) , 0< -2

true

now we draw the graph. see the attachment for graph.

common region would be solution set.

option 2 is correct.