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Finding the Fourth Proportional to 70.80, 97.70 and 39.72

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Solution

The fourth proportional to 70.80, 97.70 and 39.72 is: 54.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    70.80 : 97.70 = 39.72 : x
  2. Step 2: Convert to fraction form
    70.80/97.70 = 39.72/x
  3. Step 3: Cross multiply
    70.80x = 97.70 × 39.72
  4. Step 4: Simplify right side
    70.80x = 3,880.82
  5. Step 5: Solve for x
    x = 3,880.82/70.80
  6. Step 6: Final answer
    x = 54.81

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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.