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Finding the Fourth Proportional to 211.81, 317.80 and 90.16

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Solution

The fourth proportional to 211.81, 317.80 and 90.16 is: 135.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.81 : 317.80 = 90.16 : x
  2. Step 2: Convert to fraction form
    211.81/317.80 = 90.16/x
  3. Step 3: Cross multiply
    211.81x = 317.80 × 90.16
  4. Step 4: Simplify right side
    211.81x = 28,652.85
  5. Step 5: Solve for x
    x = 28,652.85/211.81
  6. Step 6: Final answer
    x = 135.28

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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.