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Finding the Fourth Proportional to 1,069.80, 1,605.30 and 420.99

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Solution

The fourth proportional to 1,069.80, 1,605.30 and 420.99 is: 631.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,069.80 : 1,605.30 = 420.99 : x
  2. Step 2: Convert to fraction form
    1,069.80/1,605.30 = 420.99/x
  3. Step 3: Cross multiply
    1,069.80x = 1,605.30 × 420.99
  4. Step 4: Simplify right side
    1,069.80x = 675,807.65
  5. Step 5: Solve for x
    x = 675,807.65/1,069.80
  6. Step 6: Final answer
    x = 631.72

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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.