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Finding the Fourth Proportional to 86.40, 119.28 and 64.25

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Solution

The fourth proportional to 86.40, 119.28 and 64.25 is: 88.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.40 : 119.28 = 64.25 : x
  2. Step 2: Convert to fraction form
    86.40/119.28 = 64.25/x
  3. Step 3: Cross multiply
    86.40x = 119.28 × 64.25
  4. Step 4: Simplify right side
    86.40x = 7,663.74
  5. Step 5: Solve for x
    x = 7,663.74/86.40
  6. Step 6: Final answer
    x = 88.70

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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.