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Finding the Fourth Proportional to 820.10, 1,230.15 and 388.10

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Solution

The fourth proportional to 820.10, 1,230.15 and 388.10 is: 582.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    820.10 : 1,230.15 = 388.10 : x
  2. Step 2: Convert to fraction form
    820.10/1,230.15 = 388.10/x
  3. Step 3: Cross multiply
    820.10x = 1,230.15 × 388.10
  4. Step 4: Simplify right side
    820.10x = 477,421.22
  5. Step 5: Solve for x
    x = 477,421.22/820.10
  6. Step 6: Final answer
    x = 582.15

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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.