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Finding the Fourth Proportional to 390.67, 538.80 and 315.95

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Solution

The fourth proportional to 390.67, 538.80 and 315.95 is: 435.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.67 : 538.80 = 315.95 : x
  2. Step 2: Convert to fraction form
    390.67/538.80 = 315.95/x
  3. Step 3: Cross multiply
    390.67x = 538.80 × 315.95
  4. Step 4: Simplify right side
    390.67x = 170,234.79
  5. Step 5: Solve for x
    x = 170,234.79/390.67
  6. Step 6: Final answer
    x = 435.75

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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.