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Finding the Fourth Proportional to 1,245.40, 1,718.64 and 685.90

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Solution

The fourth proportional to 1,245.40, 1,718.64 and 685.90 is: 946.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,245.40 : 1,718.64 = 685.90 : x
  2. Step 2: Convert to fraction form
    1,245.40/1,718.64 = 685.90/x
  3. Step 3: Cross multiply
    1,245.40x = 1,718.64 × 685.90
  4. Step 4: Simplify right side
    1,245.40x = 1,178,815.18
  5. Step 5: Solve for x
    x = 1,178,815.18/1,245.40
  6. Step 6: Final answer
    x = 946.54

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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.