## Probability( Standard Deviation)

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nazrulq
Contributor
Posts: 270
Joined: Sun Feb 26, 2017 6:06 am

### Probability( Standard Deviation)

Question: Project Manager Charted to deliver 5000 units that are 60 centimeters each. Upper Control Limit 63 cm
while lower control limit 57 cm. Approximately what percentage will be above 61cm?

1. 68.3%
2.31.7%
3. 95.5%
4. 15.9%

Can somebody explain!
VCAB
Participant
Posts: 73
Joined: Wed Dec 21, 2016 4:26 pm

### Re: Probability( Standard Deviation)

Well let me attempt this:
Question: Project Manager Charted to deliver 5000 units that are 60 centimeters each. Upper Control Limit 63 cm
while lower control limit 57 cm
. Approximately what percentage will be above 61cm?

The question is seeking to know the percentage that is above 61cm (that means it is only concerned about one tale of the bell curve)

First is to discover the means, which the question says is 60cm
Then we need to find the SD= P-O/6= In this question the upper limit of 63cm is the pessimistic and the lower of 57cm is the optimistic
SD= 63-57/6= 1
This means the SD from the means limits are: Mean- SD and Mean + SD=== 59-61
Since only 50% of the bell curve that we seek= 1-SD/2= 1-.683= .313/2= .1585 = 15.9%