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Finding the Fourth Proportional to 85.40, 117.92 and 71.72

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Solution

The fourth proportional to 85.40, 117.92 and 71.72 is: 99.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.40 : 117.92 = 71.72 : x
  2. Step 2: Convert to fraction form
    85.40/117.92 = 71.72/x
  3. Step 3: Cross multiply
    85.40x = 117.92 × 71.72
  4. Step 4: Simplify right side
    85.40x = 8,457.22
  5. Step 5: Solve for x
    x = 8,457.22/85.40
  6. Step 6: Final answer
    x = 99.03

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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.