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Finding the Fourth Proportional to 1,225.40, 1,690.07 and 989.28

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Solution

The fourth proportional to 1,225.40, 1,690.07 and 989.28 is: 1,364.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,225.40 : 1,690.07 = 989.28 : x
  2. Step 2: Convert to fraction form
    1,225.40/1,690.07 = 989.28/x
  3. Step 3: Cross multiply
    1,225.40x = 1,690.07 × 989.28
  4. Step 4: Simplify right side
    1,225.40x = 1,671,947.50
  5. Step 5: Solve for x
    x = 1,671,947.50/1,225.40
  6. Step 6: Final answer
    x = 1,364.42

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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.