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Finding the Fourth Proportional to 612.96, 919.20 and 420.64

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Solution

The fourth proportional to 612.96, 919.20 and 420.64 is: 630.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    612.96 : 919.20 = 420.64 : x
  2. Step 2: Convert to fraction form
    612.96/919.20 = 420.64/x
  3. Step 3: Cross multiply
    612.96x = 919.20 × 420.64
  4. Step 4: Simplify right side
    612.96x = 386,652.29
  5. Step 5: Solve for x
    x = 386,652.29/612.96
  6. Step 6: Final answer
    x = 630.80

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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.