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Finding the Fourth Proportional to 21.79, 32.81 and 19.70

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Solution

The fourth proportional to 21.79, 32.81 and 19.70 is: 29.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.79 : 32.81 = 19.70 : x
  2. Step 2: Convert to fraction form
    21.79/32.81 = 19.70/x
  3. Step 3: Cross multiply
    21.79x = 32.81 × 19.70
  4. Step 4: Simplify right side
    21.79x = 646.24
  5. Step 5: Solve for x
    x = 646.24/21.79
  6. Step 6: Final answer
    x = 29.65

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.