Page 60 - Math SL HB Sem 3

Consider X-IV (50,9), calculate

a) P(X < 57) e\P(57<x<59)
b) P(x > se) f) P(40<x<42)
c) P(x < 42) g) P(40 <X<s7)
d) P(x > 40)

The test scores of a class of students are normally distributed with a mean of 67 and a standard
deviation of 10. The mark for a distinction is 85.
Find the percentage of students achieving a distinction.

The monthly salary of a certain population is normally distributed with a mean of $18000 and a

standard deviation of $3000.
a) Find the percentage of the population that have monthly salary lower than $23000'
b) Find the percentage of the population that have monthly salary more than $13000?
c)Threepeoplearerandom|ychosenfromthepopulation'whatistheprobabilitythatallthreeof
them have salary between $15000 and $28000?

2l