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Finding the Fourth Proportional to 1,687.64, 2,329.50 and 989

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Solution

The fourth proportional to 1,687.64, 2,329.50 and 989 is: 1,365.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,687.64 : 2,329.50 = 989 : x
  2. Step 2: Convert to fraction form
    1,687.64/2,329.50 = 989/x
  3. Step 3: Cross multiply
    1,687.64x = 2,329.50 × 989
  4. Step 4: Simplify right side
    1,687.64x = 2,303,875.50
  5. Step 5: Solve for x
    x = 2,303,875.50/1,687.64
  6. Step 6: Final answer
    x = 1,365.15

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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.