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Finding the Fourth Proportional to 79.20, 109.20 and 64.60

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Solution

The fourth proportional to 79.20, 109.20 and 64.60 is: 89.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    79.20 : 109.20 = 64.60 : x
  2. Step 2: Convert to fraction form
    79.20/109.20 = 64.60/x
  3. Step 3: Cross multiply
    79.20x = 109.20 × 64.60
  4. Step 4: Simplify right side
    79.20x = 7,054.32
  5. Step 5: Solve for x
    x = 7,054.32/79.20
  6. Step 6: Final answer
    x = 89.07

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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.