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Finding the Fourth Proportional to 816.78, 1,127.30 and 485.39

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Solution

The fourth proportional to 816.78, 1,127.30 and 485.39 is: 669.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    816.78 : 1,127.30 = 485.39 : x
  2. Step 2: Convert to fraction form
    816.78/1,127.30 = 485.39/x
  3. Step 3: Cross multiply
    816.78x = 1,127.30 × 485.39
  4. Step 4: Simplify right side
    816.78x = 547,172.08
  5. Step 5: Solve for x
    x = 547,172.08/816.78
  6. Step 6: Final answer
    x = 669.91

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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.