The mean length of a cellular telephone call in 1999 was 2.38 minutes. A researcher claims that the average length of a phone call has increased since then. She conducts a survey of randomly selected 49 cellular phone users and determines the mean length to be 2.48 minutes, and standard deviation 1.8 minutes. To test the claim we would use:

The function a represents the cost of manufacturing product a, in hundreds of dollars, and the function b represents the cost of manufacturing product b, in hundreds of dollars. a(t) = 5t + 2 b(t) = 7t - 2t +4 find the expression that describes the total cost of manufacturing both products, a(t) + b(t). a. 7t^2 - 7t + 2 b. 7t^2 + 3 +6 c. 7t^2 + 7t - 6 d. 7t^2 - 3t + 6

Find the value of x that will make l ll m

Asurvey of 2,000 doctors showed that an average of 3 out of 5 doctors use brand x aspirin.how many doctors use brand x aspirin