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Finding the Fourth Proportional to 86.91, 120 and 54.19

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Solution

The fourth proportional to 86.91, 120 and 54.19 is: 74.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.91 : 120 = 54.19 : x
  2. Step 2: Convert to fraction form
    86.91/120 = 54.19/x
  3. Step 3: Cross multiply
    86.91x = 120 × 54.19
  4. Step 4: Simplify right side
    86.91x = 6,502.80
  5. Step 5: Solve for x
    x = 6,502.80/86.91
  6. Step 6: Final answer
    x = 74.82

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1.5x scale

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.