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Finding the Fourth Proportional to 1,187.80, 1,639.44 and 690.51

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Solution

The fourth proportional to 1,187.80, 1,639.44 and 690.51 is: 953.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.80 : 1,639.44 = 690.51 : x
  2. Step 2: Convert to fraction form
    1,187.80/1,639.44 = 690.51/x
  3. Step 3: Cross multiply
    1,187.80x = 1,639.44 × 690.51
  4. Step 4: Simplify right side
    1,187.80x = 1,132,053.56
  5. Step 5: Solve for x
    x = 1,132,053.56/1,187.80
  6. Step 6: Final answer
    x = 953.07

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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.