Question

At the Fort Macleod Annual Santa Claus Parade, it is known that the probability of
seeing a non-tacky float is only 1 in 5. Assuming that the floats are ordered randomly,
what is the probability that of the next 36 floats, more than 10 are non-tacky? Please show Calculations

Answer 1

If we consider "seeing a non tacky float " as a "success" then this can be though of as a binomial ,model , with n = 36 and success probability = 1/5 = 0.2

Let X be the number of floats out of 36 , which are non tacky.

So , X~ Bin ( 36 , 0.2 ) x = 0,1,2,3,...,36

So, x = 0,1,2,.......,36

To find P[X >10]

Note that :

We make the calculations in excel and find the results as below . :

	X	P[X=x]
	0	0.000325
	1	0.002921
	2	0.012778
	3	0.036204
	4	0.074671
	5	0.119474
	6	0.15432
	7	0.165343
	8	0.149842
	9	0.116544
	10	0.078667
	Total	0.911087

So, P[ X > 10] = 1- P[X <=10] = 1- 0.9111 = 0.0889 Ans