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Finding the Fourth Proportional to 1,020.72, 1,407.62 and 685.38

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Solution

The fourth proportional to 1,020.72, 1,407.62 and 685.38 is: 945.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,020.72 : 1,407.62 = 685.38 : x
  2. Step 2: Convert to fraction form
    1,020.72/1,407.62 = 685.38/x
  3. Step 3: Cross multiply
    1,020.72x = 1,407.62 × 685.38
  4. Step 4: Simplify right side
    1,020.72x = 964,751.17
  5. Step 5: Solve for x
    x = 964,751.17/1,020.72
  6. Step 6: Final answer
    x = 945.17

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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.