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Finding the Fourth Proportional to 31.80, 43.76 and 31

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Solution

The fourth proportional to 31.80, 43.76 and 31 is: 42.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.80 : 43.76 = 31 : x
  2. Step 2: Convert to fraction form
    31.80/43.76 = 31/x
  3. Step 3: Cross multiply
    31.80x = 43.76 × 31
  4. Step 4: Simplify right side
    31.80x = 1,356.41
  5. Step 5: Solve for x
    x = 1,356.41/31.80
  6. Step 6: Final answer
    x = 42.65

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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.