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Finding the Fourth Proportional to 1,009.08, 1,390.56 and 728.80

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Solution

The fourth proportional to 1,009.08, 1,390.56 and 728.80 is: 1,004.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,009.08 : 1,390.56 = 728.80 : x
  2. Step 2: Convert to fraction form
    1,009.08/1,390.56 = 728.80/x
  3. Step 3: Cross multiply
    1,009.08x = 1,390.56 × 728.80
  4. Step 4: Simplify right side
    1,009.08x = 1,013,440.13
  5. Step 5: Solve for x
    x = 1,013,440.13/1,009.08
  6. Step 6: Final answer
    x = 1,004.32

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.