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Finding the Fourth Proportional to 781.39, 1,079.85 and 641.28

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Solution

The fourth proportional to 781.39, 1,079.85 and 641.28 is: 886.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.39 : 1,079.85 = 641.28 : x
  2. Step 2: Convert to fraction form
    781.39/1,079.85 = 641.28/x
  3. Step 3: Cross multiply
    781.39x = 1,079.85 × 641.28
  4. Step 4: Simplify right side
    781.39x = 692,486.21
  5. Step 5: Solve for x
    x = 692,486.21/781.39
  6. Step 6: Final answer
    x = 886.22

Related Problems

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Half scale
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Double scale
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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.