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Finding the Fourth Proportional to 98.40, 147.72 and 78.18

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Solution

The fourth proportional to 98.40, 147.72 and 78.18 is: 117.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    98.40 : 147.72 = 78.18 : x
  2. Step 2: Convert to fraction form
    98.40/147.72 = 78.18/x
  3. Step 3: Cross multiply
    98.40x = 147.72 × 78.18
  4. Step 4: Simplify right side
    98.40x = 11,548.75
  5. Step 5: Solve for x
    x = 11,548.75/98.40
  6. Step 6: Final answer
    x = 117.37

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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.