The probability is 0.2005.
We compute the z-score for this time:
z = (X-μ)/σ = (230-184)/55 = 0.84
Looking this up in a z-table (http://www.z-table.com) we see that the area to the left of this (less than this) is 0.7995. We want the area greater than this, so we subtract this from 1:
1 - 0.7995 = 0.2005.
as you can see the x-intercept on the graph is 5
so x=5
Set the equations equal to each other and solve for x (x being the number of boats)
105+9.50x=14.75x
Subtract the 9.50x from both sides
105=5.25x
Divide by 5.25
20=x
So a member and a nonmember have to rent a boat 20 times in order to pay the same amount of money
She can dance for four months with $400 dollars