A snake oil salesman claims rubbing his brand of snake oil on your feet every ni

Question

A snake oil salesman claims rubbing his brand of snake oil on your feet every night before bed for 6 months will increase height by 1 inch on average. In the table below, you record the heights of 11 volunteers before and after they use the snake oil for a month. Is there evidence to support the salesman’s claim?

Before (inches) 65.4, 68.5, 67.2, 71.3, 73.2, 74.8, 64.7, 69.3, 65.5, 70.0, 71.1 average before = 69.1818

After (inches) 65.5, 68.8, 66.8, 71.0, 73.5, 75.0, 65.0, 69.8, 65.5, 70.2, 71.4 average after = 71.6

Explanation / Answer

Here sample mean height for before X1-bar = 69.1818

Here sample mean height for After X2-bar =69.31818

Null Hypothesis : H0 : there is on an average 1 inch increase in mean length after putting snake oil than before putting snake oil. d 1There is no difference between mean length before putting oil and after putting oil. d = 1

Alternative Hypothesis : H: There is no one inch difference between mean length before putting oil and after putting oil.  d 1

Difference Table

Test Static

mean of the differences dbar = 0.136364

Standard deviation of differences s = 0.27303

so

t = (dbar ) - (d)/ (s/n) = 0.136364 - 1 / (0.27303/11) = - 0.863636/0.08232 = - 10.49

Here we don't know the value of alpha so we will use p - value test here.Here P - value for the given T will be 0.00001 so we can reject the null hypothesis and say there is no one inch difference by putting snake oil between mean length before putting oil and after putting oil.

Before After d 65.4 65.5 0.1 68.5 68.8 0.3 67.2 66.8 -0.4 71.3 71 -0.3 73.2 73.5 0.3 74.8 75 0.2 64.7 65 0.3 69.3 69.8 0.5 65.5 65.5 0 70 70.2 0.2 71.1 71.4 0.3 sum 1.5 average 69.18182 69.31818 0.136364 std. dev. 0.27303

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.