1) A study of the effects of caffeine asked volunteers to take a memory test 2 h

Question

1) A study of the effects of caffeine asked volunteers to take a memory test 2 hours after drinking soda. Some drank caffeine-free cola, some drank regular cola (with caffeine), and others drank a mixture of the two (getting half the dose of caffeine). The boxplots to the right are for each group's scores. All are drawn using the same scale. Variable High Caffeine Low Caffeine No Caffeine d) Which group has the largest median value? (1 point) Which group has the largest range of scores? (1 point) Which group has the largest interquartile range of scores? 15 20 25 30 e) f) (1 point)

Explanation / Answer

(d)

From the boxplot, we get:

Median for High Coffeine = 20

Median for Low Coffeine = 22

Median for No Coffeine = 18

So,Low Coffienne group has the largest median value.

(e)

Range for High Coffience = 27 - 12 = 15

Range for Low Coffiene = 28 - 17 = 11

Range for No Coffiene = 23 - 11 = 12

So, High Coffienne gropu has the largest range of scores.

(f)

High Coffiene:

Q1 = 16, Q3 = 24. So, IQR = 24 - 16 = 8

Low Coffienne:

Q1 = 20, Q3 = 25. So, IQR = 25 - 20 = 5

No Coffienne:
Q1 = 17.   Q3 = 21. So, IQR = 21 - 17 = 4

So,

High Coffience group has the largest interquartile range of scores.

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