In: Statistics and Probability
Eighty-five percent of
the employees at the Smucker Company plant on Colorado Road have
their bimonthly wages sent directly to their bank by electronic
funds transfer. This is called direct deposit. Suppose we select a
random sample of twelve employees.
a) What is the probability that more than seven of them receive
their pay via direct deposit?
b) What is the probability that at least six of them receive their
pay via direct deposit?
c) List the probabilities for x =0-12. And find the mean and standard deviation of this distribution using the list of probabilities (x=0-12).
X: Number of employees receive their pay via direct deposit
P:- Percent of employee receive their pay via direct deposit
n:- Total number of employees sampled.
P=0.85 ; n = 12
X follows Binomial( n= 12, P= 0.85)
The probability mass function for X is
Let's first solve Q.c) it will help to solve first two
C)
n= 12 , P=0.85
Sr.No. | X | 12cX | (0.85)^x | (0.15)^(12-x) | P(x) |
1 | 0 | 1 | 1 | 1.3E-10 | 1.3E-10 |
2 | 1 | 12 | 0.85 | 8.6E-10 | 8.8E-09 |
3 | 2 | 66 | 0.7225 | 5.8E-09 | 2.7E-07 |
4 | 3 | 220 | 0.614125 | 3.8E-08 | 5.2E-06 |
5 | 4 | 495 | 0.522006 | 2.6E-07 | 6.6E-05 |
6 | 5 | 792 | 0.443705 | 1.7E-06 | 0.0006 |
7 | 6 | 924 | 0.37715 | 1.1E-05 | 0.0040 |
8 | 7 | 792 | 0.320577 | 7.6E-05 | 0.0193 |
9 | 8 | 495 | 0.272491 | 0.0005 | 0.0683 |
10 | 9 | 220 | 0.231617 | 0.0034 | 0.1720 |
11 | 10 | 66 | 0.196874 | 0.0225 | 0.2924 |
12 | 11 | 12 | 0.167343 | 0.15 | 0.3012 |
13 | 12 | 1 | 0.142242 | 1 | 0.1422 |
Total | 1.00 |
Above is the table for the probability of x for 0 to 12.
Sr.No. | X | P(x) | X.P(x) | X^2 | (X^2)*P(x) |
1 | 0 | 1.3E-10 | 0.00 | 0 | 0.00 |
2 | 1 | 8.8E-09 | 8.8E-09 | 1 | 8.8E-09 |
3 | 2 | 2.7E-07 | 5.5E-07 | 4 | 1.1E-06 |
4 | 3 | 5.2E-06 | 1.6E-05 | 9 | 4.7E-05 |
5 | 4 | 6.6E-05 | 0.0003 | 16 | 0.0011 |
6 | 5 | 0.0006 | 0.0030 | 25 | 0.0150 |
7 | 6 | 0.0040 | 0.0238 | 36 | 0.1429 |
8 | 7 | 0.0193 | 0.1350 | 49 | 0.9447 |
9 | 8 | 0.0683 | 0.5463 | 64 | 4.3702 |
10 | 9 | 0.1720 | 1.5478 | 81 | 13.9300 |
11 | 10 | 0.2924 | 2.9236 | 100 | 29.2358 |
12 | 11 | 0.3012 | 3.3134 | 121 | 36.4474 |
13 | 12 | 0.1422 | 1.7069 | 144 | 20.4828 |
Total | 1.00 | 10.20 | 105.57 |