Statistics (random variable)
posted by pallavi .
A contractor is interested in the total cost of a project on which he intends to bid. He estimates that materials will cost rs 25,000 and that his labour will be rs900 per day. If he the project takes X days to complete,the total cost of the project (in rupees) will be given as:
there is a table which gives the completion time, in days, for theproject.
Completion time X (days) : Probability
10 : 0.1
11 : 0.3
12 : 0.3
13 : 0.2
14 : 0.1
Find the mean and variance for completion time X.
For mean which is E(x) : i got 11.9
Variance V(x): i got 176.7
standard deviation (x), i got 5.92
Now find the mean and variance for total cost C.
Mean= c=25000 +900x
=(25000+ 900 v(x)
25000 + 900x
=25000+900 x 11.9
but am having problem to find the variance??