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Finding the Fourth Proportional to 680.72, 1,021.80 and 646.64

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Solution

The fourth proportional to 680.72, 1,021.80 and 646.64 is: 970.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    680.72 : 1,021.80 = 646.64 : x
  2. Step 2: Convert to fraction form
    680.72/1,021.80 = 646.64/x
  3. Step 3: Cross multiply
    680.72x = 1,021.80 × 646.64
  4. Step 4: Simplify right side
    680.72x = 660,736.75
  5. Step 5: Solve for x
    x = 660,736.75/680.72
  6. Step 6: Final answer
    x = 970.64

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.