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Finding the Fourth Proportional to 1,392.50, 1,921.66 and 771.50

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Solution

The fourth proportional to 1,392.50, 1,921.66 and 771.50 is: 1,064.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,392.50 : 1,921.66 = 771.50 : x
  2. Step 2: Convert to fraction form
    1,392.50/1,921.66 = 771.50/x
  3. Step 3: Cross multiply
    1,392.50x = 1,921.66 × 771.50
  4. Step 4: Simplify right side
    1,392.50x = 1,482,560.69
  5. Step 5: Solve for x
    x = 1,482,560.69/1,392.50
  6. Step 6: Final answer
    x = 1,064.68

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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.