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the data in the table represent the tuition for all 2-year community co…

Question

the data in the table represent the tuition for all 2-year community colleges in a region in 2022-2023. (a) draw a frequency ogive. (b) draw a relative frequency ogive.

tuition (dollars)number of community colleges
800-82468
825-84912
850-8745
875-8990
900-9240
925-9490
950-9742

(a) which of the following graphs is the frequency ogive?
○ a. ○ b.
graphs with cumulative freq vs tuition (774 to 974) and cumulative freq up to 120
○ c. ○ d.

Explanation:

Response
Part (a) - Drawing Frequency Ogive
Step 1: Understand Frequency Ogive

A frequency ogive (or cumulative frequency graph) is a line graph that represents the cumulative frequency of a dataset. For grouped data (like tuition ranges here), we plot the upper class boundaries on the x - axis and the cumulative frequency on the y - axis.

Step 2: Determine Class Boundaries
  • For the class \(775 - 799\), the upper class boundary is \(799.5\) (since the next class starts at \(800\), we take the mid - point between \(799\) and \(800\)).
  • For the class \(800 - 824\), the upper class boundary is \(824.5\).
  • For the class \(825 - 849\), the upper class boundary is \(849.5\).
  • For the class \(850 - 874\), the upper class boundary is \(874.5\).
  • For the class \(875 - 899\), the upper class boundary is \(899.5\).
  • For the class \(900 - 924\), the upper class boundary is \(924.5\).
  • For the class \(925 - 949\), the upper class boundary is \(949.5\).
  • For the class \(950 - 974\), the upper class boundary is \(974.5\).
Step 3: Calculate Cumulative Frequency
  • For the first class (\(775 - 799\)): Cumulative Frequency (\(CF\)) = \(20\) (since it's the first class, cumulative frequency is the frequency of the class itself).
  • For the second class (\(800 - 824\)): \(CF=20 + 68=88\)
  • For the third class (\(825 - 849\)): \(CF = 88+12 = 100\)
  • For the fourth class (\(850 - 874\)): \(CF=100 + 5=105\)
  • For the fifth class (\(875 - 899\)): \(CF = 105+0 = 105\)
  • For the sixth class (\(900 - 924\)): \(CF=105 + 0=105\)
  • For the seventh class (\(925 - 949\)): \(CF = 105+0 = 105\)
  • For the eighth class (\(950 - 974\)): \(CF=105 + 2=107\)
Step 4: Plot the Points

We plot the points \((799.5,20)\), \((824.5,88)\), \((849.5,100)\), \((874.5,105)\), \((899.5,105)\), \((924.5,105)\), \((949.5,105)\), \((974.5,107)\) and connect them with straight lines.

Part (b) - Drawing Relative Frequency Ogive
Step 1: Understand Relative Frequency Ogive

A relative frequency ogive uses cumulative relative frequency. The relative frequency of a class is \(\frac{\text{Frequency of the class}}{\text{Total number of observations}}\), and cumulative relative frequency is the sum of relative frequencies up to that class.

Step 2: Calculate Total Number of Community Colleges

Total number of community colleges \(N=20 + 68+12 + 5+0 + 0+0 + 2=107\)

Step 3: Calculate Relative Frequencies and Cumulative Relative Frequencies
  • For the class \(775 - 799\): Relative Frequency (\(RF\))=\(\frac{20}{107}\approx0.187\), Cumulative Relative Frequency (\(CRF\))=\(0.187\)
  • For the class \(800 - 824\): \(RF=\frac{68}{107}\approx0.636\), \(CRF = 0.187+0.636 = 0.823\)
  • For the class \(825 - 849\): \(RF=\frac{12}{107}\approx0.112\), \(CRF=0.823 + 0.112=0.935\)
  • For the class \(850 - 874\): \(RF=\frac{5}{107}\approx0.047\), \(CRF=0.935+0.047 = 0.982\)
  • For the class \(875 - 899\): \(RF=\frac{0}{107}=0\), \(CRF = 0.982+0 = 0.982\)
  • For the class \(900 - 924\): \(RF=\frac{0}{107}=0\), \(CRF=0.982 + 0=0.982\)
  • For the class \(925 - 949\): \(RF=\frac{0}{107}=0\), \(CRF=0.982+0 = 0.982\)
  • For the class \(950 - 974\): \(RF=\frac{2}{107}\approx0.019\), \(CRF=0.982+0.019 = 1.001\) (due to rounding)
Step 4: Plot the Points

We plot the points \((799.5,0.187)\), \((824.5,0.823)\), \((849.5,0.935)\), \((874.5,0.982)\), \((899.5,0.982)\), \((924.5,0.982)\), \((949.5,0.982)\), \((974.5,1.001)\) and connect them with straight lines.

Part (a) - Identifying the Frequency Ogive

A frequency ogive should be a non - decreasing (non - falling) graph since cum…

Answer:

(for part (a) - identifying the frequency ogive):
D