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Finding the Fourth Proportional to 85.51, 128.02 and 64.15

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Solution

The fourth proportional to 85.51, 128.02 and 64.15 is: 96.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.51 : 128.02 = 64.15 : x
  2. Step 2: Convert to fraction form
    85.51/128.02 = 64.15/x
  3. Step 3: Cross multiply
    85.51x = 128.02 × 64.15
  4. Step 4: Simplify right side
    85.51x = 8,212.48
  5. Step 5: Solve for x
    x = 8,212.48/85.51
  6. Step 6: Final answer
    x = 96.04

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.