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Finding the Fourth Proportional to 690.72, 1,042.35 and 670.20

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Solution

The fourth proportional to 690.72, 1,042.35 and 670.20 is: 1,011.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    690.72 : 1,042.35 = 670.20 : x
  2. Step 2: Convert to fraction form
    690.72/1,042.35 = 670.20/x
  3. Step 3: Cross multiply
    690.72x = 1,042.35 × 670.20
  4. Step 4: Simplify right side
    690.72x = 698,582.97
  5. Step 5: Solve for x
    x = 698,582.97/690.72
  6. Step 6: Final answer
    x = 1,011.38

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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.