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Finding the Fourth Proportional to 1,209.40, 1,668.92 and 685.42

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Solution

The fourth proportional to 1,209.40, 1,668.92 and 685.42 is: 945.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,209.40 : 1,668.92 = 685.42 : x
  2. Step 2: Convert to fraction form
    1,209.40/1,668.92 = 685.42/x
  3. Step 3: Cross multiply
    1,209.40x = 1,668.92 × 685.42
  4. Step 4: Simplify right side
    1,209.40x = 1,143,911.15
  5. Step 5: Solve for x
    x = 1,143,911.15/1,209.40
  6. Step 6: Final answer
    x = 945.85

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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.