Answer:
40
Step-by-step explanation:
The number of girls is represented by 3 parts of the ratio.
Divide number of girls by 3 to find value of one part of ratio.
= 5 ← value of 1 part of ratio, thus
5 parts = 5 × 5 = 25 ← number of boys
Total members = 15 + 25 = 40
Step-by-step explanation:
Assuming the data is as shown, restaurant X has a mean service time of 180.56, with a standard deviation of 62.6.
The standard error is SE = s/√n = 62.6/√50 = 8.85.
At 95% confidence, the critical value is z = 1.960.
Therefore, the confidence interval is:
180.56 ± 1.960 × 8.85
180.56 ± 17.35
(163, 198)
Restaurant Y has a mean service time of 152.96, with a standard deviation of 49.2.
The standard error is SE = s/√n = 49.2/√50 = 6.96.
At 95% confidence, the critical value is z = 1.960.
Therefore, the confidence interval is:
152.96 ± 1.960 × 6.96
152.96 ± 13.64
(139, 167)
