Quiz 07 Normal Curves 7.3b • Name:

1. Guava leaves have a mean leaf blade length = 11.5 centimeters with a standard deviation of σ = 1.6 cm. For this exercise assume that the leaf blade lengths are normally distributed.

  1. p(x ≤ 9) = __________ What is the probability a leaf blade length will be 9 cm or less?
  2. p(x ≤ __________) = 0.15. Fifteen percent (15%) of guava leaves are shorter than what length x? Determine that length x.
  3. p(x ≥ __________) = 0.20. Twenty percent (20%) of guava leaves are longer than what length x? Determine that length x.
  4. __________ If a tree has 500 leaves, how many leaves are as long or longer than the length in question c above?

Normal Statistics
Calculate a z value from an x z = standardize.gif (905 bytes) =STANDARDIZE(x, , σ)
Calculate an x value from a zx = z σ + =z*σ+
Find a probability p(x) from a z value where the probability p is the area to the left of z. =NORMSDIST(z)
Find a z value from a probability p, where p is the area to the left of z =NORMSINV(p)

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