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Finding the Fourth Proportional to 38.98, 53.80 and 30.78

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Solution

The fourth proportional to 38.98, 53.80 and 30.78 is: 42.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    38.98 : 53.80 = 30.78 : x
  2. Step 2: Convert to fraction form
    38.98/53.80 = 30.78/x
  3. Step 3: Cross multiply
    38.98x = 53.80 × 30.78
  4. Step 4: Simplify right side
    38.98x = 1,655.89
  5. Step 5: Solve for x
    x = 1,655.89/38.98
  6. Step 6: Final answer
    x = 42.48

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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.