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Finding the Fourth Proportional to 611.40, 843.28 and 390.12

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Solution

The fourth proportional to 611.40, 843.28 and 390.12 is: 538.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    611.40 : 843.28 = 390.12 : x
  2. Step 2: Convert to fraction form
    611.40/843.28 = 390.12/x
  3. Step 3: Cross multiply
    611.40x = 843.28 × 390.12
  4. Step 4: Simplify right side
    611.40x = 328,980.39
  5. Step 5: Solve for x
    x = 328,980.39/611.40
  6. Step 6: Final answer
    x = 538.08

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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.