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Finding the Fourth Proportional to 85.42, 117.89 and 65.72

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Solution

The fourth proportional to 85.42, 117.89 and 65.72 is: 90.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.42 : 117.89 = 65.72 : x
  2. Step 2: Convert to fraction form
    85.42/117.89 = 65.72/x
  3. Step 3: Cross multiply
    85.42x = 117.89 × 65.72
  4. Step 4: Simplify right side
    85.42x = 7,746.81
  5. Step 5: Solve for x
    x = 7,746.81/85.42
  6. Step 6: Final answer
    x = 90.70

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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.