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Finding the Fourth Proportional to 65.57, 98.40 and 42.80

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Solution

The fourth proportional to 65.57, 98.40 and 42.80 is: 64.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    65.57 : 98.40 = 42.80 : x
  2. Step 2: Convert to fraction form
    65.57/98.40 = 42.80/x
  3. Step 3: Cross multiply
    65.57x = 98.40 × 42.80
  4. Step 4: Simplify right side
    65.57x = 4,211.03
  5. Step 5: Solve for x
    x = 4,211.03/65.57
  6. Step 6: Final answer
    x = 64.23

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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.