Probability - Need Help?

A hair salon did a survey of 360 customers regarding satisfaction with service and type of customer. A walk-in customer is on who has seen no ads and not been referred. The other customers either saw a TV ad or were referred to the salon (but not both). The results are as follows:





Walk IN TV AD Referred Total


Not Satisfied 21 9 5 35


Neutral 18 25 37 80


Satisfied 36 43 59 138


Very Satisfied 28 31 48 107


Total 103 108 149 360





W= Walk-In \ TV= Saw TV ad \ R=Referred \NS= Not Satisfied \V = Very Satisfied





a. P(NS)


b. P(NS and W)


c. Given that R happened, find P(NS)


d. Given that NS happened, find P(R)


e. P(V)


f. P(V or TV)


g. P(not V)


h. Are events N and R exclusive

Probability - Need Help?
a) 35 people weren't satisfied out of a total of 360 people, so = 35/360





b) P(NS) = 35/360 (previous answer); P(W) = 103/360 to find P(NW and W) you multiply the two probabilities together. so


P(NS %26amp; W) = 103/360 * 35/360


= 103*35 / 360 * 360


= 3605 / 129600 and then simplify





c) "given that R happened", means you only count the probability of the event for people who are R. so instead of 360, you use the number of people who are R, or 149. so P(NS) is then = to 5/149





d) same principle as question c). so P(R) given N = 5/35





e) this is like question a). so answer = 107/360





f) to find this type of probability (the OR type that is) you add up the possibility of each event happening. so P(V) = 107/360 and P(TV) = 103/360 add these two together


P(V or TV) = 103/360 + 107/360


= (103 + 107) / 360


= 210 / 360





g) this means P of NS or N or S, so you add these together.


P(not V) = 35/360 + 80/360 + 138/360


= (35 + 80 + 138) / 360


= 253/360





h) mutualy exclusive means that if one event happens, then the other event cannot happen. since 37 people were both N and R, these event are NOT mutually exclusive





hope this helps you understand probability!!

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