Question

7. The following 12 data pairs relate variable xi, the amount of fertilizer, to variable Yi, the amount of wheat harvested: x: 30 30 30 50 50 50 70 70 70 90 90 90 Y: 9 11 14 12 14 23 19 22 31 29 33 35 such that : ∑x = 720 ∑y = 252 , ∑ xy =17240, ∑x2 =49200, ∑y2 = 6228 a) Find equation of linear regression line: Y = A + BX. b) 95% 2 sided confidence interval for B. c) Is there regression on input variable? d) Find 2-sided 99% prediction interval for response if x0 = 40. e) Calculate R2, explain its meaning. [5+5+5+5+5 = 25] 8. A manufacturing company of light bulb claims that an average light bulb lasts 500 days. A contractor randomly selects 30 bulbs for testing. The sampled bulbs last an average of 490 days, with a standard deviation of 100 days. If the claim were true, what is the probability that 30 randomly selected bulbs would have an average life of no more than 490 days?

Answer 1

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