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Finding the Fourth Proportional to 287.90, 431.90 and 105.31

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Solution

The fourth proportional to 287.90, 431.90 and 105.31 is: 157.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    287.90 : 431.90 = 105.31 : x
  2. Step 2: Convert to fraction form
    287.90/431.90 = 105.31/x
  3. Step 3: Cross multiply
    287.90x = 431.90 × 105.31
  4. Step 4: Simplify right side
    287.90x = 45,483.39
  5. Step 5: Solve for x
    x = 45,483.39/287.90
  6. Step 6: Final answer
    x = 157.98

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.