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Finding the Fourth Proportional to 666.08, 919.20 and 390.08

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Solution

The fourth proportional to 666.08, 919.20 and 390.08 is: 538.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    666.08 : 919.20 = 390.08 : x
  2. Step 2: Convert to fraction form
    666.08/919.20 = 390.08/x
  3. Step 3: Cross multiply
    666.08x = 919.20 × 390.08
  4. Step 4: Simplify right side
    666.08x = 358,561.54
  5. Step 5: Solve for x
    x = 358,561.54/666.08
  6. Step 6: Final answer
    x = 538.32

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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.