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Finding the Fourth Proportional to 157.90, 236.90 and 80.78

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Solution

The fourth proportional to 157.90, 236.90 and 80.78 is: 121.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    157.90 : 236.90 = 80.78 : x
  2. Step 2: Convert to fraction form
    157.90/236.90 = 80.78/x
  3. Step 3: Cross multiply
    157.90x = 236.90 × 80.78
  4. Step 4: Simplify right side
    157.90x = 19,136.78
  5. Step 5: Solve for x
    x = 19,136.78/157.90
  6. Step 6: Final answer
    x = 121.20

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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.