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The following output (from MATLAB) is for the least-squares fit of model ln y =

ID: 3224209 • Letter: T

Question

The following output (from MATLAB) is for the least-squares fit of model ln y = beta_0 + beta_1 ln x + epsilon, when represents the monthly production of a gas well and x represents the volume of fracture fluid in. (A scatterplot of these data is presented in Figure 7.22.) a. What is the equation of the least-squares line for predicting ln y from ln x? b. Predict the production of a well into which 2500 gal/ft of fluid have been pumped. c. Predict the production of a well into which 1600 gal/ft of fluid have been pumped. d. Find a 95% prediction interval for the production of a well into which 1600 gal/ft of fluid have been pump.

Explanation / Answer

SolA:

LN PROD=-0.444+0.798 LN FLUID

SOLB:

X=2500

LN PROD=-0.444+0.798(LN 2500)

=5.7996

sOLC:

X=1600

LN PROD=-0.444+0.798(LN 1600)

=5.4435

sOLD:

95% PREDICTION INTERVAL IS

3.9738, 6.9176

: