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Finding the Fourth Proportional to 72.46, 99.90 and 65.80

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Solution

The fourth proportional to 72.46, 99.90 and 65.80 is: 90.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.46 : 99.90 = 65.80 : x
  2. Step 2: Convert to fraction form
    72.46/99.90 = 65.80/x
  3. Step 3: Cross multiply
    72.46x = 99.90 × 65.80
  4. Step 4: Simplify right side
    72.46x = 6,573.42
  5. Step 5: Solve for x
    x = 6,573.42/72.46
  6. Step 6: Final answer
    x = 90.72

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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.