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Finding the Fourth Proportional to 1,389.28, 1,916.40 and 996.40

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Solution

The fourth proportional to 1,389.28, 1,916.40 and 996.40 is: 1,374.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,389.28 : 1,916.40 = 996.40 : x
  2. Step 2: Convert to fraction form
    1,389.28/1,916.40 = 996.40/x
  3. Step 3: Cross multiply
    1,389.28x = 1,916.40 × 996.40
  4. Step 4: Simplify right side
    1,389.28x = 1,909,500.96
  5. Step 5: Solve for x
    x = 1,909,500.96/1,389.28
  6. Step 6: Final answer
    x = 1,374.45

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1.5x scale

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.