Answer:
Mean = 41.588
Standard Deviation = 17.765
Step-by-step explanation:
60 - N/D = 1.03643
75 - M/D
75 - (60 - 1.03643D)/D = 1.88079
15 + 1.03643D = 1.88079D
15 = 0.84436D
17.765 = D
D = 17.765
-----------------------------------
60 - M = 1.03643D
60 - 1.03643D = M
M = 60 - 1.03643(17.765)
M = 41.588