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Finding the Fourth Proportional to 86.19, 128.52 and 75.45

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Solution

The fourth proportional to 86.19, 128.52 and 75.45 is: 112.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.19 : 128.52 = 75.45 : x
  2. Step 2: Convert to fraction form
    86.19/128.52 = 75.45/x
  3. Step 3: Cross multiply
    86.19x = 128.52 × 75.45
  4. Step 4: Simplify right side
    86.19x = 9,696.83
  5. Step 5: Solve for x
    x = 9,696.83/86.19
  6. Step 6: Final answer
    x = 112.51

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.