Spinning penny page (as of October 27, 2002)
Spinning penny*: Proportion of heads p
= (??) Sample data:
Students spun pennies 50 times each.
Fall 1999 pooled 13 students
p-hat = 321/650 = .4938
Spring 2001 pooled 15 students
p-hat = 398/750
= .531
Fall 2001 Math 251 7 students p-hat
= 174/350 = .497
Fall 2001 Math 151 9 students p-hat
= 229/450 = .509
Pooled all 43 previous
students p-hat =1122/2150 = .522
Spring 2002 Flicked: 7 students p-hat
= 157/350 = .449
Without the "10H" outlier: p-hat
= 147/300 = .49
Twirled: 13 studentsp-hat
= 296/650 = .455
Combined 20 students p-hat
= 453/1000 = .453
Sampling variability:
Distribution
of individual students' p-hats, Proportion of heads/50
o
o
o
o
o
o
o o
o
o o
o o o
o o o
o
o o o
o
o o o
o
o o o
o
o o
o o o o
o
o
o
o
o o o o o o
o
o
o
o
o o
o o o o o o
o o o o
o
-+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
.20 .22 .24 .26 .28 .30 .32 .34 .36 .38
.40 .42 .44 .46 .48 .50 .52 .54 .56 .58 .60 .62.64
Flicked:
Fall 2002 6 students p-hat = 151/300
= .503
x
x x
x x x
-+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
.20 .22 .24 .26 .28 .30 .32 .34 .36 .38
.40 .42 .44 .46 .48 .50 .52 .54 .56 .58 .60 .62.64
Twirled:
Fall 2002 8 students p-hat = 183/400
= .4575
o o
o o o
o o
o o
-+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
.20 .22 .24 .26 .28 .30 .32 .34 .36 .38
.40 .42 .44 .46 .48 .50 .52 .54 .56 .58 .60 .62.64
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*Text answer book says spinning pennies often approach 40% heads in
the long term. Not here. Are Wells Women different?!