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Finding the Fourth Proportional to 666.62, 919.70 and 390.62

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Solution

The fourth proportional to 666.62, 919.70 and 390.62 is: 538.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    666.62 : 919.70 = 390.62 : x
  2. Step 2: Convert to fraction form
    666.62/919.70 = 390.62/x
  3. Step 3: Cross multiply
    666.62x = 919.70 × 390.62
  4. Step 4: Simplify right side
    666.62x = 359,253.21
  5. Step 5: Solve for x
    x = 359,253.21/666.62
  6. Step 6: Final answer
    x = 538.92

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.