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Finding the Fourth Proportional to 421.76, 634.08 and 390.08

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Solution

The fourth proportional to 421.76, 634.08 and 390.08 is: 586.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.76 : 634.08 = 390.08 : x
  2. Step 2: Convert to fraction form
    421.76/634.08 = 390.08/x
  3. Step 3: Cross multiply
    421.76x = 634.08 × 390.08
  4. Step 4: Simplify right side
    421.76x = 247,341.93
  5. Step 5: Solve for x
    x = 247,341.93/421.76
  6. Step 6: Final answer
    x = 586.45

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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.