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Finding the Fourth Proportional to 1,315.75, 1,815.75 and 918

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Solution

The fourth proportional to 1,315.75, 1,815.75 and 918 is: 1,266.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,315.75 : 1,815.75 = 918 : x
  2. Step 2: Convert to fraction form
    1,315.75/1,815.75 = 918/x
  3. Step 3: Cross multiply
    1,315.75x = 1,815.75 × 918
  4. Step 4: Simplify right side
    1,315.75x = 1,666,858.50
  5. Step 5: Solve for x
    x = 1,666,858.50/1,315.75
  6. Step 6: Final answer
    x = 1,266.85

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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.