A Machine Is Supposed to Fill Boxes to a Weight

Essay

A machine is supposed to fill boxes to a weight of 50 lbs. Every 30 minutes a sample of four boxes is tested; the results are given below.
$$\begin{array} { r | r r r r | r | r } \mathrm { S } &&& { \mathrm { A } } && \mathrm { M } & \mathrm { R } \\\hline 1 & 49 & 38 & 39 & 45 & 42.75 & 11 \\2 & 52 & 51 & 43 & 61 & 51.75 & 18 \\3 & 56 & 60 & 32 & 52 & 50 & 28 \\4 & 44 & 59 & 46 & 49 & 49.5 & 15\\5 & 51 & 61 & 48 & 45 & 51.25 & 16 \\6 & 45 & 50 & 46 & 4 8& 47.25 & 5 \\7 & 52 & 51 & 45 & 5 & 50.75 & 10 \\8 & 40 & 50 & 53 & 48&47.75 & 13\\9 & 48 & 67 & 60 & 5 1& 56.5 & 19 \\10 & 43 & 50 & 50 & 47 & 47.5 & 7 \\11 & 48 & 30 & 38 & 39 & 38.75 & 18 \\12 & 50 & 46 & 48 & 53 & 49.25 & 7\\13 & 50 & 58 & 56 & 64 & 57 & 14 \\14 & 47 & 52 & 47 & 49 & 48.75 & 5 \\15 & 52 & 57 & 58 & 52&54.75 & 6\\\end{array}$$