Unsure of what you mean by "reference number."
I do recognize that 11pi/9 is in quadrant III. I suspect that the so-called "reference number" is the acute angle between the end ray of 11pi/9 and pi, or, in more easily comparable numbers, between 9pi/9 and 11pi/9.
That difference is 2pi/9.
7/3 is represented by a non terminating decimal (2.333...)
Answer:
90% confidence interval for the mean blood pressure of all executives is 123.12 to 129.02.
The closest option is A
Step-by-step explanation:
Confidence Interval = mean + or - Error margin (E)
mean = 126.07
sd = 15
n = 72
degree of freedom = n - 1 = 72 - 1 = 71
Confidence level (C) = 90% = 0.9
Significance level = 1 - C = 1 - 0.9 = 0.1 = 10%
t-value corresponding to 71 degrees of freedom and 10% significance level is 1.6667
E = t×sd/√n = 1.6667×15/√72 = 2.95
Lower limit = mean - E = 126.07 - 2.95 = 123.12
Upper limit = mean + E = 126.07 + 2.95 = 129.02
90% confidence interval for the mean blood pressure of all executives is between a lower limit of 123.12 and an upper limit of 129.02.
