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Finding the Fourth Proportional to 85.74, 128.03 and 71.16

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Solution

The fourth proportional to 85.74, 128.03 and 71.16 is: 106.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.74 : 128.03 = 71.16 : x
  2. Step 2: Convert to fraction form
    85.74/128.03 = 71.16/x
  3. Step 3: Cross multiply
    85.74x = 128.03 × 71.16
  4. Step 4: Simplify right side
    85.74x = 9,110.26
  5. Step 5: Solve for x
    x = 9,110.26/85.74
  6. Step 6: Final answer
    x = 106.25

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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.