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Finding the Fourth Proportional to 72.90, 100.98 and 64.80

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Solution

The fourth proportional to 72.90, 100.98 and 64.80 is: 89.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.90 : 100.98 = 64.80 : x
  2. Step 2: Convert to fraction form
    72.90/100.98 = 64.80/x
  3. Step 3: Cross multiply
    72.90x = 100.98 × 64.80
  4. Step 4: Simplify right side
    72.90x = 6,543.50
  5. Step 5: Solve for x
    x = 6,543.50/72.90
  6. Step 6: Final answer
    x = 89.76

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.