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Finding the Fourth Proportional to 781.80, 1,080.44 and 641.72

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Solution

The fourth proportional to 781.80, 1,080.44 and 641.72 is: 886.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.80 : 1,080.44 = 641.72 : x
  2. Step 2: Convert to fraction form
    781.80/1,080.44 = 641.72/x
  3. Step 3: Cross multiply
    781.80x = 1,080.44 × 641.72
  4. Step 4: Simplify right side
    781.80x = 693,339.96
  5. Step 5: Solve for x
    x = 693,339.96/781.80
  6. Step 6: Final answer
    x = 886.85

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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.