The article \"Characterization of Room Temperature Damping in Aluminum-Indium Alloys\" suggests that x= A1 matrix grain size (m) for an alloy consisting of 2% indium could be modeled with a normal distribution having =96 and =14. a) What interval (a,b) includes the central 90% of all grain sizes ( so that 5% are below a and 5% are above b)? Solution The 90% interval would be given by ± z* where z is the z score associated with a 5% probability. P(z > 1.645) = .05 Interval: 96 ± 1.645*14 = (72.97, 119.03).

1. The article "Characterization of Room Temperature Damping in Aluminum-Indium Alloys"
suggests that x= A1 matrix grain size (m) for an alloy consisting of 2% indium could be modeled
with a normal distribution having =96 and =14.
a) What interval (a,b) includes the central 90% of all grain sizes ( so that 5% are below a and 5%
are above b)?
Solution
The 90% interval would be given by ± z* where z is the z score associated with a 5%
probability.
P(z > 1.645) = .05
Interval: 96 ± 1.645*14 = (72.97, 119.03)