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In one community college, the cost per credit hour for in-state students has been increasing by $3\$3 a year. In another community college, it has been increasing by 9%9\% per year. This year, the cost is $65\$65 at both colleges. To the nearest dollar, what was the positive difference in costs 22 years ago?

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Q. In one community college, the cost per credit hour for in-state students has been increasing by $3\$3 a year. In another community college, it has been increasing by 9%9\% per year. This year, the cost is $65\$65 at both colleges. To the nearest dollar, what was the positive difference in costs 22 years ago?
  1. Calculate Cost 22 Years Ago: Calculate the cost per credit hour 22 years ago for the first community college.\newlineThe cost has been increasing by $3\$3 a year, so 22 years ago, the cost would have been $3\$3 less per year for 22 years.\newlineCost 22 years ago = Current cost - (22 years * $3/year\$3/year increase)\newline= $65\$65 - (22 * $3\$3)\newline= $65\$65 - $6\$6\newline= $59\$59
  2. Calculate Cost Increase: Calculate the cost per credit hour 22 years ago for the second community college.\newlineThe cost has been increasing by 99% per year. Let's denote the cost 22 years ago as CC.\newlineWe know that the cost this year is $65\$65, which is after two 99% increases.\newlineSo, we can set up the equation: C×(1+9%)2=$65C \times (1 + 9\%)^2 = \$65\newlineC×(1.09)2=$65C \times (1.09)^2 = \$65\newlineC=$65/(1.09)2C = \$65 / (1.09)^2\newlineC$65/1.1881C \approx \$65 / 1.1881\newlineC$54.73C \approx \$54.73, which we round to the nearest dollar to get \$\(55\).
  3. Calculate Cost Difference: Calculate the positive difference in costs per credit hour between the two colleges \(2\) years ago.\(\newline\)Difference = Cost at first college \(2\) years ago - Cost at second college \(2\) years ago\(\newline\)= \(\$59\) - \(\$55\)\(\newline\)= \(\$4\)

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