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Finding the Fourth Proportional to 390.80, 538.16 and 316.56

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Solution

The fourth proportional to 390.80, 538.16 and 316.56 is: 435.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.80 : 538.16 = 316.56 : x
  2. Step 2: Convert to fraction form
    390.80/538.16 = 316.56/x
  3. Step 3: Cross multiply
    390.80x = 538.16 × 316.56
  4. Step 4: Simplify right side
    390.80x = 170,359.93
  5. Step 5: Solve for x
    x = 170,359.93/390.80
  6. Step 6: Final answer
    x = 435.93

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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.