Statistics Questions

Twenty Long-Evans rats have been trained on a brightness discrimination task. Their scores (errors) are as follows:
6 8 9 6
6 5 4 12
9 8 4 5
6 6 7 8
6 7 11 7

Arrange the data into a frequency distribution, and use the distribution to solve the following problems.

The cumulative percentage of rats making 6 or fewer errors is
80%.
50%.
65%.
90%.

The real limits of the score of 20 are
19–21.
19.5–20.5.
19.75–20.25.
20–20.

The scores on an exam in history of psychology are shown in the following frequency distribution. Use the distribution to solve the following problems.

X f    X f    X f    X f
95 2    66 1    49 1    30 1
85 1    64 1    42 1    28 1
83 1    63 1    41 2    26 1
81 1    56 1    40 2    23 1
78 1    52 1    34 1    22 1
72 2    51 1    31 1

What percentage of students scored below 72?
70.37%
77.78%
25.93%
59.26%

How many students scored 85 or below?
24
21
25
26

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IQ          Frequency
4 – 5           4
6 – 7           9
8 – 9           5
10 – 11          1
12 – 13          1

1) 10/20=50%

To find the answer you count the number of Long-Evans rats that scored 6 or less mistakes {6,6,6,5,4,4,5,6,6,6} and divide by the total number of rats – this was given in the question prompt (20)....