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Finding the Fourth Proportional to 85.55, 128.21 and 70.35

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Solution

The fourth proportional to 85.55, 128.21 and 70.35 is: 105.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.55 : 128.21 = 70.35 : x
  2. Step 2: Convert to fraction form
    85.55/128.21 = 70.35/x
  3. Step 3: Cross multiply
    85.55x = 128.21 × 70.35
  4. Step 4: Simplify right side
    85.55x = 9,019.22
  5. Step 5: Solve for x
    x = 9,019.22/85.55
  6. Step 6: Final answer
    x = 105.43

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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.