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Finding the Fourth Proportional to 157.79, 217.95 and 121.40

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Solution

The fourth proportional to 157.79, 217.95 and 121.40 is: 167.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    157.79 : 217.95 = 121.40 : x
  2. Step 2: Convert to fraction form
    157.79/217.95 = 121.40/x
  3. Step 3: Cross multiply
    157.79x = 217.95 × 121.40
  4. Step 4: Simplify right side
    157.79x = 26,459.13
  5. Step 5: Solve for x
    x = 26,459.13/157.79
  6. Step 6: Final answer
    x = 167.69

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.