The number of miles travelled per week by a motorist is distributed normally with a mean of 640 & a standard deviation of 50. If the car's petrol consumption is 30 miles per gallon, calculate the probability that the motorist will use less than 80 gallons of petrol over a period of 4 weeks. Ans: 0.0548
My working:
D~N(640,502) 4D~N(nµ,n2s2)~N(2560,40000)
80 gallons travels 2400 miles. P(4D<2400)=P(Z<)=P(Z<-0.8) But is wrong answer. Please explain with full working.
My working:
D~N(640,502) 4D~N(nµ,n2s2)~N(2560,40000)
80 gallons travels 2400 miles. P(4D<2400)=P(Z<)=P(Z<-0.8) But is wrong answer. Please explain with full working.
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I think the answer you have considers that the 4 weeks are 28 days.So 2240 miles
P((2240-2560)/200)=P(-1.6)=0.0548
P((2240-2560)/200)=P(-1.6)=0.0548