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Finding the Fourth Proportional to 1,315.40, 1,974.09 and 665.78

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Solution

The fourth proportional to 1,315.40, 1,974.09 and 665.78 is: 999.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,315.40 : 1,974.09 = 665.78 : x
  2. Step 2: Convert to fraction form
    1,315.40/1,974.09 = 665.78/x
  3. Step 3: Cross multiply
    1,315.40x = 1,974.09 × 665.78
  4. Step 4: Simplify right side
    1,315.40x = 1,314,309.64
  5. Step 5: Solve for x
    x = 1,314,309.64/1,315.40
  6. Step 6: Final answer
    x = 999.17

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.