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Finding the Fourth Proportional to 989.87, 1,365.50 and 919.51

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Solution

The fourth proportional to 989.87, 1,365.50 and 919.51 is: 1,268.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.87 : 1,365.50 = 919.51 : x
  2. Step 2: Convert to fraction form
    989.87/1,365.50 = 919.51/x
  3. Step 3: Cross multiply
    989.87x = 1,365.50 × 919.51
  4. Step 4: Simplify right side
    989.87x = 1,255,589.79
  5. Step 5: Solve for x
    x = 1,255,589.79/989.87
  6. Step 6: Final answer
    x = 1,268.45

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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.