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Finding the Fourth Proportional to 38.78, 53.43 and 31.49

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Solution

The fourth proportional to 38.78, 53.43 and 31.49 is: 43.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    38.78 : 53.43 = 31.49 : x
  2. Step 2: Convert to fraction form
    38.78/53.43 = 31.49/x
  3. Step 3: Cross multiply
    38.78x = 53.43 × 31.49
  4. Step 4: Simplify right side
    38.78x = 1,682.51
  5. Step 5: Solve for x
    x = 1,682.51/38.78
  6. Step 6: Final answer
    x = 43.39

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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.