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Finding the Fourth Proportional to 1,689.60, 2,331.60 and 990.72

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Solution

The fourth proportional to 1,689.60, 2,331.60 and 990.72 is: 1,367.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,689.60 : 2,331.60 = 990.72 : x
  2. Step 2: Convert to fraction form
    1,689.60/2,331.60 = 990.72/x
  3. Step 3: Cross multiply
    1,689.60x = 2,331.60 × 990.72
  4. Step 4: Simplify right side
    1,689.60x = 2,309,962.75
  5. Step 5: Solve for x
    x = 2,309,962.75/1,689.60
  6. Step 6: Final answer
    x = 1,367.17

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1.5x scale

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.