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Finding the Fourth Proportional to 212.51, 318.54 and 90.65

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Solution

The fourth proportional to 212.51, 318.54 and 90.65 is: 135.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.51 : 318.54 = 90.65 : x
  2. Step 2: Convert to fraction form
    212.51/318.54 = 90.65/x
  3. Step 3: Cross multiply
    212.51x = 318.54 × 90.65
  4. Step 4: Simplify right side
    212.51x = 28,875.65
  5. Step 5: Solve for x
    x = 28,875.65/212.51
  6. Step 6: Final answer
    x = 135.88

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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.