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Finding the Fourth Proportional to 71.31, 98.40 and 42.18

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Solution

The fourth proportional to 71.31, 98.40 and 42.18 is: 58.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    71.31 : 98.40 = 42.18 : x
  2. Step 2: Convert to fraction form
    71.31/98.40 = 42.18/x
  3. Step 3: Cross multiply
    71.31x = 98.40 × 42.18
  4. Step 4: Simplify right side
    71.31x = 4,150.51
  5. Step 5: Solve for x
    x = 4,150.51/71.31
  6. Step 6: Final answer
    x = 58.20

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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.