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1zephyr

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I dunno where i can post this but you guys are good at maths

A car manufacturer takes an average of 17.5 hours to construct a car. This includes time for stamping, welding, painting, assembly and inspections. Construction times vary with a standard deviation of 30 minutes and these times follow a normal distribution

b. What is the probability that a randomly selected car manufactured at this plant takes between 18 and 19 hours to construct?

c. Find the probability that the construction time for a randomly selected car manufactured at this plant is less than 17 hours and 50 minutes.

Pretty sure ive done it wrong can anyone help?
questionc.JPGquestionb.JPG
 

InteGrand

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I dunno where i can post this but you guys are good at maths

A car manufacturer takes an average of 17.5 hours to construct a car. This includes time for stamping, welding, painting, assembly and inspections. Construction times vary with a standard deviation of 30 minutes and these times follow a normal distribution

b. What is the probability that a randomly selected car manufactured at this plant takes between 18 and 19 hours to construct?

c. Find the probability that the construction time for a randomly selected car manufactured at this plant is less than 17 hours and 50 minutes.

Pretty sure ive done it wrong can anyone help?
View attachment 32352View attachment 32351
I think you've done it right.















http://www.sinclair.edu/centers/mathlab/pub/findyourcourse/worksheets/Statistics/Z-Table.pdf





















 
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1zephyr

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ok sweet
thanks for taking the time to show us your working
 

1zephyr

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follow up
Find the construction time of a car which is on the 10th percentile of this distribution.
I need to draw a probability distribution plot but i dont know what to put in the mean and standard deviation as the results i get dont seem right
Can anyone possibly make a graph
 

InteGrand

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