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Finding the Fourth Proportional to 1,128.37, 1,690.50 and 780.73

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Solution

The fourth proportional to 1,128.37, 1,690.50 and 780.73 is: 1,169.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,128.37 : 1,690.50 = 780.73 : x
  2. Step 2: Convert to fraction form
    1,128.37/1,690.50 = 780.73/x
  3. Step 3: Cross multiply
    1,128.37x = 1,690.50 × 780.73
  4. Step 4: Simplify right side
    1,128.37x = 1,319,824.07
  5. Step 5: Solve for x
    x = 1,319,824.07/1,128.37
  6. Step 6: Final answer
    x = 1,169.67

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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.