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Finding the Fourth Proportional to 1,287.90, 1,777.28 and 728.35

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Solution

The fourth proportional to 1,287.90, 1,777.28 and 728.35 is: 1,005.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.90 : 1,777.28 = 728.35 : x
  2. Step 2: Convert to fraction form
    1,287.90/1,777.28 = 728.35/x
  3. Step 3: Cross multiply
    1,287.90x = 1,777.28 × 728.35
  4. Step 4: Simplify right side
    1,287.90x = 1,294,473.80
  5. Step 5: Solve for x
    x = 1,294,473.80/1,287.90
  6. Step 6: Final answer
    x = 1,005.11

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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.