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Finding the Fourth Proportional to 721, 996.78 and 690.40

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Solution

The fourth proportional to 721, 996.78 and 690.40 is: 954.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    721 : 996.78 = 690.40 : x
  2. Step 2: Convert to fraction form
    721/996.78 = 690.40/x
  3. Step 3: Cross multiply
    721x = 996.78 × 690.40
  4. Step 4: Simplify right side
    721x = 688,176.91
  5. Step 5: Solve for x
    x = 688,176.91/721
  6. Step 6: Final answer
    x = 954.48

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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.