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Finding the Fourth Proportional to 86.40, 130.21 and 84.71

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Solution

The fourth proportional to 86.40, 130.21 and 84.71 is: 127.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.40 : 130.21 = 84.71 : x
  2. Step 2: Convert to fraction form
    86.40/130.21 = 84.71/x
  3. Step 3: Cross multiply
    86.40x = 130.21 × 84.71
  4. Step 4: Simplify right side
    86.40x = 11,030.20
  5. Step 5: Solve for x
    x = 11,030.20/86.40
  6. Step 6: Final answer
    x = 127.66

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.