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Finding the Fourth Proportional to 1,412.68, 2,118.84 and 643

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Solution

The fourth proportional to 1,412.68, 2,118.84 and 643 is: 964.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,412.68 : 2,118.84 = 643 : x
  2. Step 2: Convert to fraction form
    1,412.68/2,118.84 = 643/x
  3. Step 3: Cross multiply
    1,412.68x = 2,118.84 × 643
  4. Step 4: Simplify right side
    1,412.68x = 1,362,414.12
  5. Step 5: Solve for x
    x = 1,362,414.12/1,412.68
  6. Step 6: Final answer
    x = 964.42

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1.5x scale

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.