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# STATS Q on 2 sided hypothesis watch

1. A factory makes both rods and copper tubes, with diameters expressed in
millimetres. Due to variations in the manufacturing process, it is known
that the internal diameter of a copper tube is N (22, 0.4²), while the diameter
of a rod is N (21.5, 0.3²).

• Find the proportion of tubes with an internal diameter less than
21.4mm.
• Find the proportion of rods with a diameter greater than 21.4mm
• Find the proportion of rods with a diameter between 21.6mm and
21.8mm.
• A rod and tube are chosen at random. Find the probability that the
rod will not pass through the tube.
2. 1) tube: T~N (22, 0.4²)
So you want P(T < 21.4)

Which part did you want help with?

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Updated: April 1, 2011
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