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Finding the Fourth Proportional to 780.72, 1,166.46 and 642.18

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Solution

The fourth proportional to 780.72, 1,166.46 and 642.18 is: 959.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.72 : 1,166.46 = 642.18 : x
  2. Step 2: Convert to fraction form
    780.72/1,166.46 = 642.18/x
  3. Step 3: Cross multiply
    780.72x = 1,166.46 × 642.18
  4. Step 4: Simplify right side
    780.72x = 749,077.28
  5. Step 5: Solve for x
    x = 749,077.28/780.72
  6. Step 6: Final answer
    x = 959.47

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.