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Finding the Fourth Proportional to 211.92, 317.76 and 90.15

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Solution

The fourth proportional to 211.92, 317.76 and 90.15 is: 135.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.92 : 317.76 = 90.15 : x
  2. Step 2: Convert to fraction form
    211.92/317.76 = 90.15/x
  3. Step 3: Cross multiply
    211.92x = 317.76 × 90.15
  4. Step 4: Simplify right side
    211.92x = 28,646.06
  5. Step 5: Solve for x
    x = 28,646.06/211.92
  6. Step 6: Final answer
    x = 135.17

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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.