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Finding the Fourth Proportional to 1,389.87, 1,917.68 and 851.36

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Solution

The fourth proportional to 1,389.87, 1,917.68 and 851.36 is: 1,174.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,389.87 : 1,917.68 = 851.36 : x
  2. Step 2: Convert to fraction form
    1,389.87/1,917.68 = 851.36/x
  3. Step 3: Cross multiply
    1,389.87x = 1,917.68 × 851.36
  4. Step 4: Simplify right side
    1,389.87x = 1,632,636.04
  5. Step 5: Solve for x
    x = 1,632,636.04/1,389.87
  6. Step 6: Final answer
    x = 1,174.67

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1.5x scale

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.