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Finding the Fourth Proportional to 867.80, 1,307.79 and 781.25

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Solution

The fourth proportional to 867.80, 1,307.79 and 781.25 is: 1,177.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    867.80 : 1,307.79 = 781.25 : x
  2. Step 2: Convert to fraction form
    867.80/1,307.79 = 781.25/x
  3. Step 3: Cross multiply
    867.80x = 1,307.79 × 781.25
  4. Step 4: Simplify right side
    867.80x = 1,021,704.40
  5. Step 5: Solve for x
    x = 1,021,704.40/867.80
  6. Step 6: Final answer
    x = 1,177.35

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.