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Finding the Fourth Proportional to 211.74, 317.61 and 90

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Solution

The fourth proportional to 211.74, 317.61 and 90 is: 135

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.74 : 317.61 = 90 : x
  2. Step 2: Convert to fraction form
    211.74/317.61 = 90/x
  3. Step 3: Cross multiply
    211.74x = 317.61 × 90
  4. Step 4: Simplify right side
    211.74x = 28,584.90
  5. Step 5: Solve for x
    x = 28,584.90/211.74
  6. Step 6: Final answer
    x = 135

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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.