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Finding the Fourth Proportional to 101.25, 139.80 and 79.20

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Solution

The fourth proportional to 101.25, 139.80 and 79.20 is: 109.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    101.25 : 139.80 = 79.20 : x
  2. Step 2: Convert to fraction form
    101.25/139.80 = 79.20/x
  3. Step 3: Cross multiply
    101.25x = 139.80 × 79.20
  4. Step 4: Simplify right side
    101.25x = 11,072.16
  5. Step 5: Solve for x
    x = 11,072.16/101.25
  6. Step 6: Final answer
    x = 109.35

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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.