Question

A quick survey of peanut butter prices had standard deviation and mean of $0.26 and $3.68, respectively. Compute the area for a peanut butter jar costing between $3.50 and $4.25.

Answer 1

Solution :

Given that ,

mean =   = $3.68

standard deviation = = $0.26   

P($3.50< x <$4.25 ) = P[(3.50-3.68) /0.26 < (x - ) / < (4.25-3.68) /0.26 )]

= P( -0.69< Z < 2.19)

= P(Z <2.19 ) - P(Z <-0.69 )

Using z table   

= 0.9857-0.2451

probability= 0.7406