Test 02 Normal Curves Chapter 7.3 • Name:

1. For the following curves A, B, and C determine the mean � and the standard deviation σ:

2. Twelve fruit bats from the lagoon islands of Chuuk state were measured and found to have a mean skull length � of 44.708 mm with a standard deviation σ of 0.593 mm. Presume that the distribution of skull lengths is normally distributed about the mean.

1. __________ What is the probability a lagoon fruit bat will have a skull length shorter than 44.115 mm?
2. __________ What is the probability a lagoon fruit bat will have a skull length longer than 45.880 mm?
3. __________ What will be the length x shorter than which the shortest 2.28% (0.0228) of the lagoon bat skulls will be found?
4. __________ What will be the length x beyond which the longest 5% of the lagoon bat skulls will be found?

Statistic or Parameter	Symbol	Equations	Excel
Calculate a z value from an x	z	=	=STANDARDIZE(x, �, σ)
Calculate an x value from a z	x	= z * σ + �	= z*σ+�
Find a probability p from a z value (the area to the left of z)			=NORMSDIST(z)
Find a z value from a probability p (from the area p to the left of z)			=NORMSINV(p)