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Finding the Fourth Proportional to 1,287.81, 1,777.10 and 728.39

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Solution

The fourth proportional to 1,287.81, 1,777.10 and 728.39 is: 1,005.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.81 : 1,777.10 = 728.39 : x
  2. Step 2: Convert to fraction form
    1,287.81/1,777.10 = 728.39/x
  3. Step 3: Cross multiply
    1,287.81x = 1,777.10 × 728.39
  4. Step 4: Simplify right side
    1,287.81x = 1,294,428.13
  5. Step 5: Solve for x
    x = 1,294,428.13/1,287.81
  6. Step 6: Final answer
    x = 1,005.14

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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.