Mechanical Engineering - Industrial Engineering and Production Management - Discussion
Discussion Forum : Industrial Engineering and Production Management - Section 2 (Q.No. 6)
6.
A PERT network has three activities on critical path with mean time 3, 8 and 6 and standard deviations 1, 2 and 2 respectively. The probability that the project will be completed in 20 days is
Discussion:
27 comments Page 2 of 3.
Sushant Bhalla said:
9 years ago
Check the table @Jerrin.
Chigumbura said:
9 years ago
Standard deviation = square root of (variance) = square root of (1 * 1 + 2 * 2 + 2 * 2) = square root of (9) = 3.
D = 20.
S = 3 + 8 + 6 = 17.
Probability = (D - S)/standard deviation = 1.
Now, from Z table probability = 0.84.
D = 20.
S = 3 + 8 + 6 = 17.
Probability = (D - S)/standard deviation = 1.
Now, from Z table probability = 0.84.
Jayesh Chavda said:
9 years ago
Which Z table? @Chigumbura.
Nerellakarthik said:
8 years ago
What is Z table?
Dishant said:
8 years ago
Why 1*1?
Harsh said:
8 years ago
I am not getting it, please explain in detail.
UCHIHA said:
7 years ago
Explanation for z=1.
Remember normal curve is symmetrical hence for z=0 the probability is 50%
now if you see chart for 6σ, it is 99.97%, for 4σ it is 95.95% and for 2σ it is 68%.
For 6σ it implies 3σ on both sides of z=0 line on a normal curve and that implies z=3.
Hence for z=1, it implies 1σ and for 1σ it is 68/2=34%,
Hence we go here for z=1 as 50%+34%=84%,
Henceforth remember it!
Remember normal curve is symmetrical hence for z=0 the probability is 50%
now if you see chart for 6σ, it is 99.97%, for 4σ it is 95.95% and for 2σ it is 68%.
For 6σ it implies 3σ on both sides of z=0 line on a normal curve and that implies z=3.
Hence for z=1, it implies 1σ and for 1σ it is 68/2=34%,
Hence we go here for z=1 as 50%+34%=84%,
Henceforth remember it!
(3)
Nir said:
7 years ago
3+8+6=17.
Standard deviation 1+2+2=5,
20-17/5=0.6.
So, I think the answer is 0.66.
Standard deviation 1+2+2=5,
20-17/5=0.6.
So, I think the answer is 0.66.
(1)
Sumit Patil said:
7 years ago
Yeah, 0. 66 is right. I agree @Nir.
Pawan said:
6 years ago
Yeah, 0.66 is right the right one.
(1)
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