In a mid-size company, the distribution of the number of phone calls answered each day by each of the 12 receptionists is bell-shaped and has a mean of 48 and a standard deviation of 9. Using the Standard Deviation Rule (as presented in the book), what is the approximate percentage of daily phone calls numbering between 30 and 66?

95.44%

Step-by-step explanation:

Mean (m) = 48

Standard deviation (sd) = 9

n = 12

Zscore = (x - m) /sd

X = 30

Zscore = (30 - 48) / 9

Zscore = - 2

X = 66

Zscore = (66 - 48) / 9

Zscore = 2

percentage of daily phone calls numbering between 30 and 66 = P(z < 2) - p(z < - 2)

P(z < 2) = 0.9772

P(z < - 2) = 0.0228

Hence,

0.9772 - 0.0228 = 0.9544

0.9544 * 100% = 95.44

hope it you

step-by-step explanation:

sin(7pi/6 - pi/3)  

= sin(7pi/6 - 2pi/6)  

= sin(5pi/6)  

= sin(pi - pi/6)  

= sin(pi/6)  

= 1/2  

sin 7pi/6 - sin pi/3  

= sin (pi + pi/6) - sin pi/3  

= -sin pi/6 - sin pi/3  

= -1/2 - sqrt(3)/2  

= -(1+sqrt(3))2

25% is the answer