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Finding the Fourth Proportional to 1,123.80, 1,685.70 and 771.45

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Solution

The fourth proportional to 1,123.80, 1,685.70 and 771.45 is: 1,157.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,123.80 : 1,685.70 = 771.45 : x
  2. Step 2: Convert to fraction form
    1,123.80/1,685.70 = 771.45/x
  3. Step 3: Cross multiply
    1,123.80x = 1,685.70 × 771.45
  4. Step 4: Simplify right side
    1,123.80x = 1,300,433.27
  5. Step 5: Solve for x
    x = 1,300,433.27/1,123.80
  6. Step 6: Final answer
    x = 1,157.18

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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.