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Finding the Fourth Proportional to 39, 53.85 and 30.86

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Solution

The fourth proportional to 39, 53.85 and 30.86 is: 42.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    39 : 53.85 = 30.86 : x
  2. Step 2: Convert to fraction form
    39/53.85 = 30.86/x
  3. Step 3: Cross multiply
    39x = 53.85 × 30.86
  4. Step 4: Simplify right side
    39x = 1,661.81
  5. Step 5: Solve for x
    x = 1,661.81/39
  6. Step 6: Final answer
    x = 42.61

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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.