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Finding the Fourth Proportional to 212.75, 318.78 and 90.93

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Solution

The fourth proportional to 212.75, 318.78 and 90.93 is: 136.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.75 : 318.78 = 90.93 : x
  2. Step 2: Convert to fraction form
    212.75/318.78 = 90.93/x
  3. Step 3: Cross multiply
    212.75x = 318.78 × 90.93
  4. Step 4: Simplify right side
    212.75x = 28,986.67
  5. Step 5: Solve for x
    x = 28,986.67/212.75
  6. Step 6: Final answer
    x = 136.25

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.