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Finding the Fourth Proportional to 1,009.40, 1,517.70 and 987.80

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Solution

The fourth proportional to 1,009.40, 1,517.70 and 987.80 is: 1,485.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,009.40 : 1,517.70 = 987.80 : x
  2. Step 2: Convert to fraction form
    1,009.40/1,517.70 = 987.80/x
  3. Step 3: Cross multiply
    1,009.40x = 1,517.70 × 987.80
  4. Step 4: Simplify right side
    1,009.40x = 1,499,184.06
  5. Step 5: Solve for x
    x = 1,499,184.06/1,009.40
  6. Step 6: Final answer
    x = 1,485.22

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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.