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Finding the Fourth Proportional to 390.36, 538.65 and 215.70

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Solution

The fourth proportional to 390.36, 538.65 and 215.70 is: 297.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.36 : 538.65 = 215.70 : x
  2. Step 2: Convert to fraction form
    390.36/538.65 = 215.70/x
  3. Step 3: Cross multiply
    390.36x = 538.65 × 215.70
  4. Step 4: Simplify right side
    390.36x = 116,186.81
  5. Step 5: Solve for x
    x = 116,186.81/390.36
  6. Step 6: Final answer
    x = 297.64

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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.