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Finding the Fourth Proportional to 28, 41.88 and 21.18

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Solution

The fourth proportional to 28, 41.88 and 21.18 is: 31.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    28 : 41.88 = 21.18 : x
  2. Step 2: Convert to fraction form
    28/41.88 = 21.18/x
  3. Step 3: Cross multiply
    28x = 41.88 × 21.18
  4. Step 4: Simplify right side
    28x = 887.02
  5. Step 5: Solve for x
    x = 887.02/28
  6. Step 6: Final answer
    x = 31.68

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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.