H0: = 21
Ha: < 21
= (18 + 19.1 + 19.2 + 18.8 + 18.4 + 19 + 18.5 + 16.1 + 16.8 + 18.2 + 14 + 17 + 13.6 + 17.5 + 20 + 20.2 + 18.8 + 18 + 23.2 + 19.4)/20 = 18.19
z = ()/()
= (18.19 - 21)/(1.8/)
= -6.98
P-value = P(Z < -6.98)
= 0.000
At the 0.05 significance level, since the P-value is less than the significance level(0 < 0.05), so we should reject H0.
Option - D) There is sufficient evidence that the average tip percentage , when bad news is delivered , is lower than the average tip percentage overall. Random chance explains the small value of observed.
People tend to be more generous after receiving good news. Are they less generous after receiving...
updated Question 5 of 9 > People tend to be more generous after receiving good news. Are they less generous after receiving bad news? The average tip left by adult Americans is 21%. Give 20 patrons of a restaurant a message on their bill warning them that tomorrow's weather will be bad and record the percentage tip they leave. Given are the tips as a percentage of the total bill. 18 19.1 19.2 18.8 18.4 19 18.5 16.1 16.8 18.2...