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Finding the Fourth Proportional to 1,209.70, 1,669.38 and 685.72

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Solution

The fourth proportional to 1,209.70, 1,669.38 and 685.72 is: 946.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,209.70 : 1,669.38 = 685.72 : x
  2. Step 2: Convert to fraction form
    1,209.70/1,669.38 = 685.72/x
  3. Step 3: Cross multiply
    1,209.70x = 1,669.38 × 685.72
  4. Step 4: Simplify right side
    1,209.70x = 1,144,727.25
  5. Step 5: Solve for x
    x = 1,144,727.25/1,209.70
  6. Step 6: Final answer
    x = 946.29

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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.