Answer:
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
50.24 cm, the equation is 2 x 3.14 x 8 cm (radius)
