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Finding the Fourth Proportional to 680.36, 1,020 and 642.20

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Solution

The fourth proportional to 680.36, 1,020 and 642.20 is: 962.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    680.36 : 1,020 = 642.20 : x
  2. Step 2: Convert to fraction form
    680.36/1,020 = 642.20/x
  3. Step 3: Cross multiply
    680.36x = 1,020 × 642.20
  4. Step 4: Simplify right side
    680.36x = 655,044
  5. Step 5: Solve for x
    x = 655,044/680.36
  6. Step 6: Final answer
    x = 962.79

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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.