My knowledge on probability topics is a bit rusty, so I was hoping you guys could help me.
Let X be the amount of products a person buys.
The probability that the person buys 1 to 12 is 60%.
From 13 to 20, 35%.
From 21 to 100, 5%.
I need to find the expected number of products he/she buys.
I did (12-1)*0.6 + (20-13)*0.35 + (100-21)*0.05 = 13.
Is that correct?
it should be (1+2+...+12)(0.6/12) + (13+...+20)(0.35/8)+(21+...+100)(0.05/80)