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Finding the Fourth Proportional to 85.76, 118.40 and 64

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Solution

The fourth proportional to 85.76, 118.40 and 64 is: 88.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.76 : 118.40 = 64 : x
  2. Step 2: Convert to fraction form
    85.76/118.40 = 64/x
  3. Step 3: Cross multiply
    85.76x = 118.40 × 64
  4. Step 4: Simplify right side
    85.76x = 7,577.60
  5. Step 5: Solve for x
    x = 7,577.60/85.76
  6. Step 6: Final answer
    x = 88.36

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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.