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Finding the Fourth Proportional to 1,311.10, 1,809.35 and 721.64

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Solution

The fourth proportional to 1,311.10, 1,809.35 and 721.64 is: 995.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311.10 : 1,809.35 = 721.64 : x
  2. Step 2: Convert to fraction form
    1,311.10/1,809.35 = 721.64/x
  3. Step 3: Cross multiply
    1,311.10x = 1,809.35 × 721.64
  4. Step 4: Simplify right side
    1,311.10x = 1,305,699.33
  5. Step 5: Solve for x
    x = 1,305,699.33/1,311.10
  6. Step 6: Final answer
    x = 995.88

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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.