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Finding the Fourth Proportional to 990.87, 1,478.62 and 859.65

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Solution

The fourth proportional to 990.87, 1,478.62 and 859.65 is: 1,282.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.87 : 1,478.62 = 859.65 : x
  2. Step 2: Convert to fraction form
    990.87/1,478.62 = 859.65/x
  3. Step 3: Cross multiply
    990.87x = 1,478.62 × 859.65
  4. Step 4: Simplify right side
    990.87x = 1,271,095.68
  5. Step 5: Solve for x
    x = 1,271,095.68/990.87
  6. Step 6: Final answer
    x = 1,282.81

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.