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Finding the Fourth Proportional to 72.12, 99.45 and 70.20

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Solution

The fourth proportional to 72.12, 99.45 and 70.20 is: 96.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.12 : 99.45 = 70.20 : x
  2. Step 2: Convert to fraction form
    72.12/99.45 = 70.20/x
  3. Step 3: Cross multiply
    72.12x = 99.45 × 70.20
  4. Step 4: Simplify right side
    72.12x = 6,981.39
  5. Step 5: Solve for x
    x = 6,981.39/72.12
  6. Step 6: Final answer
    x = 96.80

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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.