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Finding the Fourth Proportional to 390.09, 538.27 and 215.40

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Solution

The fourth proportional to 390.09, 538.27 and 215.40 is: 297.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.09 : 538.27 = 215.40 : x
  2. Step 2: Convert to fraction form
    390.09/538.27 = 215.40/x
  3. Step 3: Cross multiply
    390.09x = 538.27 × 215.40
  4. Step 4: Simplify right side
    390.09x = 115,943.36
  5. Step 5: Solve for x
    x = 115,943.36/390.09
  6. Step 6: Final answer
    x = 297.22

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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.