Assume the weights of cows can be described by N(1160,85). a) 6) Exactly what pe
ID: 3043146 • Letter: A
Question
Assume the weights of cows can be described by N(1160,85). a) 6) Exactly what percent, to the nearest tenth of a percent, of the cows weigh less than 1200 pounds? Draw a picture and shade the relevant portion of the normal curve. b) In which interval of weights do the middle 60% of the cows mentioned in #3 fall? c) The heaviest ten percent of the cows weigh more than how many pounds? 7) Explain in a paragraph when you should use Normalcdf and when you should use invNorm to answer questions about the normal curve. 8) a) Create a sample problem (with solution) that should be solved using Normaledf b) Create a sample problem (with solution) that should be solved using invNormExplanation / Answer
mean is 1160 and s is 85
a) P(x<1200)=P(z<(1200-1160)/85)=P(z<0.47) . from normal distribution table it is 0.6808
b) for middle 60%, the upper z value will be given as the area to the left of curve which is 20+60 i.e 80%. thus z for 0.8 is 0.84, the -ve z value will be fo 0.2 area which is -0.84
thus answer is 1160+0.84*85=1231.4 and the lower limit is 1160-0.84*85=1088.6
c) for the heaviest 10%, we need to look at the value is 90% from left of curve which has z value of 1.28 from normal distribution table. thus answer is 1160+1.28*85=1268.8