NAME: ____________________________________________ Date: ______________ Period: _________
Math Quiz 2
Determining X2
X2 = Σ (O-E)2
E
A bag of M&M was purchased for a science experiment on probability. The teacher counted 100 M&Ms. The data are
listed below. Her hypothesis was: If there are four colors of M&Ms, there should be an equal number of each
M& Ms for each color. Calculate X2 and determine if this experiment was successful.
Color of M&M
Brown
Yellow
Green
Orange
Observed (O)
22
24
29
25
(12 points possible)
Expected (E)
O-E
25
25
25
25
(O-E)2
(O-E)2/E
(3 points) X2 = Σ _______________
(2 Points)
Degrees of Freedom
1
2
3
4
Probability
0.01
6.64
9.21
11.3
13.2
0.05
3.84
5.99
7.82
9.49
(2 Points)
Did she Accept or Reject her Hypothesis (2 points)
Degrees of Freedom: _________
Circle:
ACCEPT
0.001
10.8
13.8
16.3
18.5
Critical Value from the chart above: _________
REJECT
Why did she accept or reject her hypothesis? (4 Points possible)
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Color of M&M
Brown
Yellow
Green
Orange
Observed (O)
22
24
29
25
(12 points possible)(1 point per square)
Expected (E)
O-E
25
-3
25
-1
25
+4
25
0
(O-E)2
9
1
16
0
(O-E)2/E
0.36
0.04
0.64
0.00
(3 points) X2 = Σ _____1.04
(2 Points)
Degrees of Freedom
1
2
3
4
Probability
0.01
6.64
9.21
11.3
13.2
0.05
3.84
5.99
7.82
9.49
(2 Points)
Did she Accept or Reject her Hypothesis (2 points)
Degrees of Freedom: __3
Circle:
ACCEPT
0.001
10.8
13.8
16.3
18.5
Critical Value from the chart above: __7.82
REJECT
Why did she accept or reject her hypothesis? (4 Points possible)
The critical value of 7.82 is greater than the X2 of 1.04 (2 points)
This indicates that the only difference between the observed and the expected is chance. (2 Points)