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Finding the Fourth Proportional to 38.40, 53.00 and 21.81

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Solution

The fourth proportional to 38.40, 53.00 and 21.81 is: 30.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    38.40 : 53.00 = 21.81 : x
  2. Step 2: Convert to fraction form
    38.40/53.00 = 21.81/x
  3. Step 3: Cross multiply
    38.40x = 53.00 × 21.81
  4. Step 4: Simplify right side
    38.40x = 1,155.82
  5. Step 5: Solve for x
    x = 1,155.82/38.40
  6. Step 6: Final answer
    x = 30.10

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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.