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Finding the Fourth Proportional to 1,312.90, 1,812.05 and 815.74

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Solution

The fourth proportional to 1,312.90, 1,812.05 and 815.74 is: 1,125.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,312.90 : 1,812.05 = 815.74 : x
  2. Step 2: Convert to fraction form
    1,312.90/1,812.05 = 815.74/x
  3. Step 3: Cross multiply
    1,312.90x = 1,812.05 × 815.74
  4. Step 4: Simplify right side
    1,312.90x = 1,478,161.67
  5. Step 5: Solve for x
    x = 1,478,161.67/1,312.90
  6. Step 6: Final answer
    x = 1,125.88

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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.