Let x = day of observation and y = number of locusts per square meter during a locust infestation in a region of North Africa.

(a) Draw a scatter diagram of the (x, y) data pairs. Do you think a straight line will be a good ­t to these data? Do the y values almost seem to explode as time goes on?

(b) Now consider a transformation y' = log y. We are using common logarithms of base 10. Draw a scatter diagram of the (x, y') data pairs and compare this diagram with the diagram of part (a). Which graph appears to better ­t a straight line?

(c) Use a calculator with regression keys to fi­nd the linear regression equation for the data pairs 1x, yoe2. What is the correlation coef­ficient?

(d) The exponential growth model is y = αβ^x. Estimate a and b and write the exponential growth equation.

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