If the foot length of women follows a normal distributio with a mean of 23 cm, and 81.5% have a foot length between 20 cm and 29 cm, what is your estimate of the standard deviation of the lengths in this population? A. 2.25cm
B. 3cm
C. 4.5cm
D. 9cm

How can you find the conditional probability of a given b as the fraction of b’s outcomes that also belong to a, and interpret the answer in terms of the model? i just need a good explanation

Mr and mrs smith buy tickets for themselves and their four children. the cost of an adult ticket is ? 6 more than the adult ticket. the total cost of the six tickets is ? 40.50 work out the cost of an adult ticket. in your working let c be the cost of the child ticket and a be the cost of the adult ticket.

Find the x-intercepts of the parabola withvertex (1,1) and y-intercept (0,-3).write your answer in this form: (x1,if necessary, round to the nearest hundredth.