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Finding the Fourth Proportional to 42.93, 64.36 and 21.28

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Solution

The fourth proportional to 42.93, 64.36 and 21.28 is: 31.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.93 : 64.36 = 21.28 : x
  2. Step 2: Convert to fraction form
    42.93/64.36 = 21.28/x
  3. Step 3: Cross multiply
    42.93x = 64.36 × 21.28
  4. Step 4: Simplify right side
    42.93x = 1,369.58
  5. Step 5: Solve for x
    x = 1,369.58/42.93
  6. Step 6: Final answer
    x = 31.90

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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.