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Finding the Fourth Proportional to 1,815.90, 2,505.94 and 987.90

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Solution

The fourth proportional to 1,815.90, 2,505.94 and 987.90 is: 1,363.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,815.90 : 2,505.94 = 987.90 : x
  2. Step 2: Convert to fraction form
    1,815.90/2,505.94 = 987.90/x
  3. Step 3: Cross multiply
    1,815.90x = 2,505.94 × 987.90
  4. Step 4: Simplify right side
    1,815.90x = 2,475,618.13
  5. Step 5: Solve for x
    x = 2,475,618.13/1,815.90
  6. Step 6: Final answer
    x = 1,363.30

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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.