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Finding the Fourth Proportional to 921.90, 1,271.52 and 711.78

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Solution

The fourth proportional to 921.90, 1,271.52 and 711.78 is: 981.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    921.90 : 1,271.52 = 711.78 : x
  2. Step 2: Convert to fraction form
    921.90/1,271.52 = 711.78/x
  3. Step 3: Cross multiply
    921.90x = 1,271.52 × 711.78
  4. Step 4: Simplify right side
    921.90x = 905,042.51
  5. Step 5: Solve for x
    x = 905,042.51/921.90
  6. Step 6: Final answer
    x = 981.71

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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.