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Finding the Fourth Proportional to 211.79, 317.74 and 128.49

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Solution

The fourth proportional to 211.79, 317.74 and 128.49 is: 192.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.79 : 317.74 = 128.49 : x
  2. Step 2: Convert to fraction form
    211.79/317.74 = 128.49/x
  3. Step 3: Cross multiply
    211.79x = 317.74 × 128.49
  4. Step 4: Simplify right side
    211.79x = 40,826.41
  5. Step 5: Solve for x
    x = 40,826.41/211.79
  6. Step 6: Final answer
    x = 192.77

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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.