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Finding the Fourth Proportional to 648.40, 972.64 and 390.16

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Solution

The fourth proportional to 648.40, 972.64 and 390.16 is: 585.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    648.40 : 972.64 = 390.16 : x
  2. Step 2: Convert to fraction form
    648.40/972.64 = 390.16/x
  3. Step 3: Cross multiply
    648.40x = 972.64 × 390.16
  4. Step 4: Simplify right side
    648.40x = 379,485.22
  5. Step 5: Solve for x
    x = 379,485.22/648.40
  6. Step 6: Final answer
    x = 585.26

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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.