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# 4. The average monthly gasoline purchase for a family with

### Resolved Question:

4. The average monthly gasoline purchase for a family with 2 cars is 80 gallons. This statistic has a normal distribution with a standard deviation of 15 gallons. A family with two cars is chosen at random.

(a) Find the probability that the family’s monthly gaoline purchases will be between 75 and 85 gallons.

(b) Find the probability that the family’s monthly gasoline purchases will be less than 75 gallons.

(c) Find the probability that the family’s monthly gasoline purchases will be more than 85 gallons
Submitted: 6 years ago.
Category: Math Homework
Expert:  abozer replied 6 years ago.

abozer :

Hi again,

JACUSTOMER-7yewrnq3- :

hi...thanks for helping me...

abozer :

a.
= P(75 < x < 85)
= P((75 - 80)/15 < z < (85 - 80)/15)
= P(-0.33 < z < 0.33)
= 0.2611

abozer :

= P(x < 75)
= P(z < (75 - 80)/15)
= P(z < -0.33)
= 0.3694

abozer :

that was b,

abozer :

c)

abozer :

= P(x > 85)
= P(z > (85 - 80)/15)
= P(z > 0.33)
= 0.3694

abozer :

Let me know if you have any questions.

JACUSTOMER-7yewrnq3- :

Thanks....I actually got the same answers when I did it!!!!