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Finding the Fourth Proportional to 79.61, 109.72 and 64.80

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Solution

The fourth proportional to 79.61, 109.72 and 64.80 is: 89.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    79.61 : 109.72 = 64.80 : x
  2. Step 2: Convert to fraction form
    79.61/109.72 = 64.80/x
  3. Step 3: Cross multiply
    79.61x = 109.72 × 64.80
  4. Step 4: Simplify right side
    79.61x = 7,109.94
  5. Step 5: Solve for x
    x = 7,109.94/79.61
  6. Step 6: Final answer
    x = 89.32

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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.