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Finding the Fourth Proportional to 1,578.85, 2,180.19 and 990.40

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Solution

The fourth proportional to 1,578.85, 2,180.19 and 990.40 is: 1,367.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,578.85 : 2,180.19 = 990.40 : x
  2. Step 2: Convert to fraction form
    1,578.85/2,180.19 = 990.40/x
  3. Step 3: Cross multiply
    1,578.85x = 2,180.19 × 990.40
  4. Step 4: Simplify right side
    1,578.85x = 2,159,260.18
  5. Step 5: Solve for x
    x = 2,159,260.18/1,578.85
  6. Step 6: Final answer
    x = 1,367.62

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Double scale
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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.