In a study of 205 adults, the mean heart rate was 75 beats per minute. assume the population of heart rates is known to be approximately normal with a standard deviation of 8 beats per minute. what is the 95% confidence interval for the mean beats per minute?

a. 73.9 − 76.1
b. 73.7 − 76.1
c. 73.9 − 76.3
d. 70.9 − 73.3

If x = 12 and y = 3, what is the value of x - y 2? 81 6 3 18

For what values of the variable x is the expression square root of 7x+14+ square root of 7-x a real number?

Ariana starts with 100 milligrams of a radioactive substance. the amount of the substance decreases by 20% each week for a number of weeks, w. the expression 100(1−0.2)w finds the amount of radioactive substance remaining after w weeks. which statement about this expression is true? a) it is the difference between the initial amount and the percent decrease. b) it is the difference between the initial amount and the decay factor after w weeks. c) it is the initial amount raised to the decay factor after w weeks. d) it is the product of the initial amount and the decay factor after w weeks.