If we draw a straight line through the points in a scatter diagram and most of the points fall close to the line,there must be a positive relationship between the two variables.

Thompson Lubricating store has the following credit terms: "The finance charge, if any, is based on the previous balance before payments or credits are deducted. The rates are 1.5% per month up to $1,300 and 1.3% per month on amounts in excess of $1,300. These are annual percentage rates of 15.7% and 13.02%, respectively. There is no finance charge if the full amount of the new balance is paid within 30 days after the cycle closing date."Compute the finance charge and the new balance for the two customers shown below. Assume that both payments were made within the 30-day period.
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