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Finding the Fourth Proportional to 42.79, 64.23 and 21.46

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Solution

The fourth proportional to 42.79, 64.23 and 21.46 is: 32.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.79 : 64.23 = 21.46 : x
  2. Step 2: Convert to fraction form
    42.79/64.23 = 21.46/x
  3. Step 3: Cross multiply
    42.79x = 64.23 × 21.46
  4. Step 4: Simplify right side
    42.79x = 1,378.38
  5. Step 5: Solve for x
    x = 1,378.38/42.79
  6. Step 6: Final answer
    x = 32.21

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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.