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Finding the Fourth Proportional to 781.16, 1,171.68 and 261.11

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Solution

The fourth proportional to 781.16, 1,171.68 and 261.11 is: 391.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.16 : 1,171.68 = 261.11 : x
  2. Step 2: Convert to fraction form
    781.16/1,171.68 = 261.11/x
  3. Step 3: Cross multiply
    781.16x = 1,171.68 × 261.11
  4. Step 4: Simplify right side
    781.16x = 305,931.51
  5. Step 5: Solve for x
    x = 305,931.51/781.16
  6. Step 6: Final answer
    x = 391.64

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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.