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Finding the Fourth Proportional to 31.25, 42.80 and 29.40

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Solution

The fourth proportional to 31.25, 42.80 and 29.40 is: 40.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.25 : 42.80 = 29.40 : x
  2. Step 2: Convert to fraction form
    31.25/42.80 = 29.40/x
  3. Step 3: Cross multiply
    31.25x = 42.80 × 29.40
  4. Step 4: Simplify right side
    31.25x = 1,258.17
  5. Step 5: Solve for x
    x = 1,258.17/31.25
  6. Step 6: Final answer
    x = 40.27

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.