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Finding the Fourth Proportional to 823.40, 1,235.10 and 391.40

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Solution

The fourth proportional to 823.40, 1,235.10 and 391.40 is: 587.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    823.40 : 1,235.10 = 391.40 : x
  2. Step 2: Convert to fraction form
    823.40/1,235.10 = 391.40/x
  3. Step 3: Cross multiply
    823.40x = 1,235.10 × 391.40
  4. Step 4: Simplify right side
    823.40x = 483,418.14
  5. Step 5: Solve for x
    x = 483,418.14/823.40
  6. Step 6: Final answer
    x = 587.10

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Double scale
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Similar ratio
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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.