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Finding the Fourth Proportional to 639.24, 957.12 and 420.12

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Solution

The fourth proportional to 639.24, 957.12 and 420.12 is: 629.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.24 : 957.12 = 420.12 : x
  2. Step 2: Convert to fraction form
    639.24/957.12 = 420.12/x
  3. Step 3: Cross multiply
    639.24x = 957.12 × 420.12
  4. Step 4: Simplify right side
    639.24x = 402,105.25
  5. Step 5: Solve for x
    x = 402,105.25/639.24
  6. Step 6: Final answer
    x = 629.04

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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.