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Finding the Fourth Proportional to 1,380.90, 1,905.44 and 813.50

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Solution

The fourth proportional to 1,380.90, 1,905.44 and 813.50 is: 1,122.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,380.90 : 1,905.44 = 813.50 : x
  2. Step 2: Convert to fraction form
    1,380.90/1,905.44 = 813.50/x
  3. Step 3: Cross multiply
    1,380.90x = 1,905.44 × 813.50
  4. Step 4: Simplify right side
    1,380.90x = 1,550,075.44
  5. Step 5: Solve for x
    x = 1,550,075.44/1,380.90
  6. Step 6: Final answer
    x = 1,122.51

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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.