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Finding the Fourth Proportional to 1,220.38, 1,683.70 and 689.20

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Solution

The fourth proportional to 1,220.38, 1,683.70 and 689.20 is: 950.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,220.38 : 1,683.70 = 689.20 : x
  2. Step 2: Convert to fraction form
    1,220.38/1,683.70 = 689.20/x
  3. Step 3: Cross multiply
    1,220.38x = 1,683.70 × 689.20
  4. Step 4: Simplify right side
    1,220.38x = 1,160,406.04
  5. Step 5: Solve for x
    x = 1,160,406.04/1,220.38
  6. Step 6: Final answer
    x = 950.86

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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.