On average, a person’s heart beats about 4.2×107 times per year. There are about 7,600,000,000 people in the world. Use this data to approximate the number of heartbeats for all the people in the world per year. Expressing your answer in scientific notation in the form a×10b, what are the values of a and b?

What is the length of the segment, endpoints of which are intersections of parabolas y=x2? 11 4 x? 7 4 and y=? 7 8 x2+x+ 31 8 ?

In a survey of 1015 adults, a polling agency asked, "when you retire, do you think you will have enough money to live comfortably or not. of the 1015 surveyed, 534 stated that they were worried about having enough money to live comfortably in retirement. construct a 90% confidence interval for the proportion of adults who are worried about having enough money to live comfortably in retirement.

Graph the system of equations on your graph paper to answer the question. {y=−x+4y=x−2 what is the solution for the system of equations? enter your answer in the boxes.