Ramina found the length of two pieces of ribbon to be 47.6 inches and 39.75 inches. which is an effective estimation strategy for finding the sum of the two lengths? round 39.75 to 30 and 47.6 to 40, then add. round 39.75 to 40 and 47.6 to 48, then add. add 47.6 and 39.75, then round the answer. subtract 39.75 from 47.6, then round the answer.

For f(x)=2x+1 and g(x)= x^2 -7, find (f•g)(x)

Ab and bc form a right angle at point b. if a= (-3,-1) and b= (4,4) what is the equation of bc?

Aprisoner is trapped in a cell containing three doors. the first door leads to a tunnel that returns him to his cell after two days of travel. the second leads to a tunnel that returns him to his cell after three days of travel. the third door leads immediately to freedom. (a) assuming that the prisoner will always select doors 1, 2 and 3 with probabili- ties 0.5,0.3,0.2 (respectively), what is the expected number of days until he reaches freedom? (b) assuming that the prisoner is always equally likely to choose among those doors that he has not used, what is the expected number of days until he reaches freedom? (in this version, if the prisoner initially tries door 1, for example, then when he returns to the cell, he will now select only from doors 2 and 3.) (c) for parts (a) and (b), find the variance of the number of days until the prisoner reaches freedom. hint for part (b): define ni to be the number of additional days the prisoner spends after initially choosing door i and returning to his cell.