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Finding the Fourth Proportional to 421.40, 630.79 and 385.51

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Solution

The fourth proportional to 421.40, 630.79 and 385.51 is: 577.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.40 : 630.79 = 385.51 : x
  2. Step 2: Convert to fraction form
    421.40/630.79 = 385.51/x
  3. Step 3: Cross multiply
    421.40x = 630.79 × 385.51
  4. Step 4: Simplify right side
    421.40x = 243,173.93
  5. Step 5: Solve for x
    x = 243,173.93/421.40
  6. Step 6: Final answer
    x = 577.07

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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.