A salon and spa chain periodically analyzes its service times to check for variation in service processes. To do this, it uses R-charts. Seven samples, each containing observed service time with three different customers, were collected. The average mean and the average range of the service times are found to be 9.924 and 0.957, respectively. If D 4 for the R-chart is 1.924, the upper control limit (UCLr=D4*Rbar) for the R-chart will be:

How to solve a simultaneous equation involved with fractions?

Michelle and julie work at a catering company. they need to bake 264 cookies for a birthday party that starts in a little over an hour and a half. each tube of cookie dough claims to make 36 cookies, but michelle eats about 1/5 of every tube and julie makes cookies that are 1.5 times as large as the recommended cookie size.it takes about 8 minutes to bake a container of cookies, but since julie's cookies are larger, they take 12 minutes to bake. a. how many tubes should each girl plan to bake? how long does each girl use the oven? b. explain your solution process what did you make? c. what assumptions did you make?

What is the interquartile range of this data set? 2, 5, 9, 11, 18, 30, 42, 48, 55, 73, 81