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Finding the Fourth Proportional to 15.90, 23.80 and 13.90

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Solution

The fourth proportional to 15.90, 23.80 and 13.90 is: 20.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.90 : 23.80 = 13.90 : x
  2. Step 2: Convert to fraction form
    15.90/23.80 = 13.90/x
  3. Step 3: Cross multiply
    15.90x = 23.80 × 13.90
  4. Step 4: Simplify right side
    15.90x = 330.63
  5. Step 5: Solve for x
    x = 330.63/15.90
  6. Step 6: Final answer
    x = 20.80

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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.