psuinstructurecom A resistor utilize ork Midnight Mocha is a

psu.instructure.com A resistor utilize ork Midnight Mocha is a 24-hour café that specializes in coffee drinks. It has a driv 1 pts DQuestion 2 Deluxe Detailing prides itself on its craftsmanship, but lately, it\'s been having problems with paint jobs on the hoods of its custom cars. Below, you\'ll find data on the number of scratches on 20 different hoods. (For most people, the scratches would be almost unnoticeable, but given its reputation, they pose a concern for Deluxe Detailing.) 1 2345 6789 10 Scratches2 86 4 5 1 3 5 11 6 Hoods Hoods 11 12 13 14 15 16 17 18 19 20 Scratches3 How many hoods, if any, are out of control using 3 standard deviations?

Solution

Using c-chart:

c = Number of defects/Number of samples = (2+8+6+4+...........................+1+8)/20 = 80/20 = 4

UCL = c + z*sqrt(c)

LCL = c - z*sqrt(c)

z = 3 (Using 3 standard deviation)

UCL = 4 + 3*sqrt(4) = 10

LCL = 4 - 3*sqrt(4) = -2 Hence, 0

The out of control is Hood 9 with 11 scratches

Hence, 1