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Finding the Fourth Proportional to 390.11, 538.35 and 215.45

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Solution

The fourth proportional to 390.11, 538.35 and 215.45 is: 297.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.11 : 538.35 = 215.45 : x
  2. Step 2: Convert to fraction form
    390.11/538.35 = 215.45/x
  3. Step 3: Cross multiply
    390.11x = 538.35 × 215.45
  4. Step 4: Simplify right side
    390.11x = 115,987.51
  5. Step 5: Solve for x
    x = 115,987.51/390.11
  6. Step 6: Final answer
    x = 297.32

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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.