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Finding the Fourth Proportional to 728.90, 1,005.45 and 518.75

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Solution

The fourth proportional to 728.90, 1,005.45 and 518.75 is: 715.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    728.90 : 1,005.45 = 518.75 : x
  2. Step 2: Convert to fraction form
    728.90/1,005.45 = 518.75/x
  3. Step 3: Cross multiply
    728.90x = 1,005.45 × 518.75
  4. Step 4: Simplify right side
    728.90x = 521,577.19
  5. Step 5: Solve for x
    x = 521,577.19/728.90
  6. Step 6: Final answer
    x = 715.57

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1.5x scale

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.