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Finding the Fourth Proportional to 98.40, 147.60 and 87.20

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Solution

The fourth proportional to 98.40, 147.60 and 87.20 is: 130.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    98.40 : 147.60 = 87.20 : x
  2. Step 2: Convert to fraction form
    98.40/147.60 = 87.20/x
  3. Step 3: Cross multiply
    98.40x = 147.60 × 87.20
  4. Step 4: Simplify right side
    98.40x = 12,870.72
  5. Step 5: Solve for x
    x = 12,870.72/98.40
  6. Step 6: Final answer
    x = 130.80

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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.