3 Suppose you want to test statistically whether or not a gi
3. Suppose you want to test (statistically) whether or not a given coin is biased . So you toss the coin 30 (independent) times, then observe the number of heads X that turns up and set the following decision rule:
Accept if Ho: p=1/2 if 5<x<25
Reject Ho:p=1/2
and accept the alternative hypothesis if Ha: p= 1/2X 5 or X 25
. (3 pts) Calculate / tabulate for p = .1, .2, .3, .4, .5, .6, .7, .8, .9 b. (5 pts) Graph versus p using Excel. Discuss your graph. c. (5 pts) Get a quarter and toss it 30 times and record the number of heads. On the basis of this outcome, state whether you will accept or reject according to the decision rule set out above.
| x | P1 | P2 | P3 | P4 | P5 | P6 | P7 | P8 | P9 | 
| 0 | 0.04239 | 0.00124 | 0.00002 | 0 | 0 | 0 | 0 | 0 | 0 | 
| 1 | 0.1837 | 0.01052 | 0.00031 | 0 | 0 | 0 | 0 | 0 | 0 | 
| 2 | 0.41135 | 0.04418 | 0.00211 | 0.00005 | 0 | 0 | 0 | 0 | 0 | 
| 3 | 0.64744 | 0.12271 | 0.00932 | 0.00031 | 0 | 0 | 0 | 0 | 0 | 
| 4 | 0.82451 | 0.25523 | 0.03015 | 0.00151 | 0.00003 | 0 | 0 | 0 | 0 | 
| 5 | 0.92681 | 0.42751 | 0.07659 | 0.00566 | 0.00016 | 0 | 0 | 0 | 0 | 
| 6 | 0.97417 | 0.60697 | 0.15952 | 0.01718 | 0.00072 | 0.00001 | 0 | 0 | 0 | 
| 7 | 0.99222 | 0.76079 | 0.28138 | 0.04352 | 0.00261 | 0.00005 | 0 | 0 | 0 | 
| 8 | 0.99798 | 0.87135 | 0.43152 | 0.09401 | 0.00806 | 0.00022 | 0 | 0 | 0 | 
| 9 | 0.99955 | 0.93891 | 0.58881 | 0.17629 | 0.02139 | 0.00086 | 0.00001 | 0 | 0 | 
| 10 | 0.99991 | 0.97438 | 0.73037 | 0.29147 | 0.04937 | 0.00285 | 0.00004 | 0 | 0 | 
| 11 | 0.99998 | 0.99051 | 0.84068 | 0.43109 | 0.10024 | 0.0083 | 0.00016 | 0 | 0 | 
| 12 | 1 | 0.99689 | 0.91553 | 0.57847 | 0.1808 | 0.02124 | 0.00063 | 0 | 0 | 
| 13 | 1 | 0.9991 | 0.95995 | 0.7145 | 0.29233 | 0.04811 | 0.00212 | 0.00001 | 0 | 
| 14 | 1 | 0.99977 | 0.98306 | 0.82463 | 0.42777 | 0.09706 | 0.00637 | 0.00005 | 0 | 
| 15 | 1 | 0.99995 | 0.99363 | 0.90294 | 0.57223 | 0.17537 | 0.01694 | 0.00023 | 0 | 
| 16 | 1 | 0.99999 | 0.99788 | 0.95189 | 0.70767 | 0.2855 | 0.04005 | 0.0009 | 0 | 
| 17 | 1 | 1 | 0.99937 | 0.97876 | 0.8192 | 0.42153 | 0.08447 | 0.00311 | 0 | 
| 18 | 1 | 1 | 0.99984 | 0.9917 | 0.89976 | 0.56891 | 0.15932 | 0.00949 | 0.00002 | 
| 19 | 1 | 1 | 0.99996 | 0.99715 | 0.95063 | 0.70853 | 0.26963 | 0.02562 | 0.00009 | 
| 20 | 1 | 1 | 0.99999 | 0.99914 | 0.97861 | 0.82371 | 0.41119 | 0.06109 | 0.00045 | 
| 21 | 1 | 1 | 1 | 0.99978 | 0.99194 | 0.90599 | 0.56848 | 0.12865 | 0.00202 | 
| 22 | 1 | 1 | 1 | 0.99995 | 0.99739 | 0.95648 | 0.71862 | 0.23921 | 0.00778 | 
| 23 | 1 | 1 | 1 | 0.99999 | 0.99928 | 0.98282 | 0.84048 | 0.39303 | 0.02583 | 
| 24 | 1 | 1 | 1 | 1 | 0.99984 | 0.99434 | 0.92341 | 0.57249 | 0.07319 | 
| 25 | 1 | 1 | 1 | 1 | 0.99997 | 0.99849 | 0.96985 | 0.74477 | 0.17549 | 
| 26 | 1 | 1 | 1 | 1 | 1 | 0.99969 | 0.99068 | 0.87729 | 0.35256 | 
| 27 | 1 | 1 | 1 | 1 | 1 | 0.99995 | 0.99789 | 0.95582 | 0.58865 | 
| 28 | 1 | 1 | 1 | 1 | 1 | 1 | 0.99969 | 0.98948 | 0.8163 | 
| 29 | 1 | 1 | 1 | 1 | 1 | 1 | 0.99998 | 0.99876 | 0.95761 | 
| 30 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 
Solution
Sample size = 30 ( I.e use Z test)
H0 p = 1/2 5 < x < 25
Probability of head = 1/2
Probability of tails = 1/2
If p = 1/2 then it\'s not baised else it\'s baised.
Mu = n p = 30 x 1/2 = 15
S.d = Root npq = root 30 x 1/2 x1/2 = 2.738
Z = (5 - 15) / 5.476 < Z(x) < (25 - 15 ) / (2.738 / root 30) = 10 / 5.476
=0.9663 - .0336 = 0.9327
Accept H0
That\'s means the coin is not baised.


