Draw back-to-back stemplots for the following data. What conclusions can you draw?

(a) The pulse rates of 30 company directors were measured before and after taking exercise. Before: 110, 93, 81, 75, 73, 73, 48, 53, 69, 69, 66, 111, 105, 93, 90, 50, 57, 64, 90, 111, 91, 70, 70, 51, 79, 93, 105, 51, 66, 93. After: 117, 81, 77, 108, 130, 69, 77, 84, 84, 86, 95, 125, 96, 104, 104, 137, 143, 70, 80, 131, 145, 106, 130, 109, 137, 75, 104, 75, 97, 80. (Use class intervals 40-49, 50-59, 60-69,...)

(b) The ages of teachers in two schools: School A: 51, 45, 33, 37, 37, 27, 28, 54, 54, 61, 34, 31, 39, 23, 53, 59, 40, 46, 48, 48, 39, 33, 25, 31, 48, 40, 53, 51, 46, 45, 45, 48, 39, 29, 23, 37. School B: 59, 56, 40, 43, 46, 38, 29, 52, 54, 34, 23, 41, 42, 52, 50, 58, 60, 45, 45, 56, 59, 49, 44, 36, 38, 25, 56, 36, 42, 47, 50, 54, 59, 47, 58, 57. (Use class intervals 20-29, 30-39, 40-49,...)

(c) 20 boys and 20 girls took part in a reaction- timing experiment. Their results were measured to the nearest hundredth of a second. Girls: 0.22, 0.21, 0.18, 0.18, 0.16, 0.19, 0.25, 0.22, 0.17, 0.19, 0.16, 0.21, 0.24, 0.22, 0.19, 0.22, 0.25, 0.22, 0.17, 0.22. Boys: 0.14, 0.20, 0.22, 0.16, 0.19, 0.16, 0.15, 0.23, 0.23, 0.19, 0.16, 0.15, 0.09, 0.23, 0.11, 0.21, 0.22, 0.18, 0.18, 0.16. (Use class intervals 0.08-0.09, 0.10-0.11, 0.12-0.13,...)