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Finding the Fourth Proportional to 1,278, 1,916.64 and 412.20

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Solution

The fourth proportional to 1,278, 1,916.64 and 412.20 is: 618.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,278 : 1,916.64 = 412.20 : x
  2. Step 2: Convert to fraction form
    1,278/1,916.64 = 412.20/x
  3. Step 3: Cross multiply
    1,278x = 1,916.64 × 412.20
  4. Step 4: Simplify right side
    1,278x = 790,039.01
  5. Step 5: Solve for x
    x = 790,039.01/1,278
  6. Step 6: Final answer
    x = 618.18

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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.