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Finding the Fourth Proportional to 210.69, 315.99 and 66.42

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Solution

The fourth proportional to 210.69, 315.99 and 66.42 is: 99.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    210.69 : 315.99 = 66.42 : x
  2. Step 2: Convert to fraction form
    210.69/315.99 = 66.42/x
  3. Step 3: Cross multiply
    210.69x = 315.99 × 66.42
  4. Step 4: Simplify right side
    210.69x = 20,988.06
  5. Step 5: Solve for x
    x = 20,988.06/210.69
  6. Step 6: Final answer
    x = 99.62

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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.