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Finding the Fourth Proportional to 999.62, 1,378.56 and 721.70

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Solution

The fourth proportional to 999.62, 1,378.56 and 721.70 is: 995.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    999.62 : 1,378.56 = 721.70 : x
  2. Step 2: Convert to fraction form
    999.62/1,378.56 = 721.70/x
  3. Step 3: Cross multiply
    999.62x = 1,378.56 × 721.70
  4. Step 4: Simplify right side
    999.62x = 994,906.75
  5. Step 5: Solve for x
    x = 994,906.75/999.62
  6. Step 6: Final answer
    x = 995.28

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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.