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Finding the Fourth Proportional to 1,261.15, 1,889.99 and 643.56

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Solution

The fourth proportional to 1,261.15, 1,889.99 and 643.56 is: 964.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,261.15 : 1,889.99 = 643.56 : x
  2. Step 2: Convert to fraction form
    1,261.15/1,889.99 = 643.56/x
  3. Step 3: Cross multiply
    1,261.15x = 1,889.99 × 643.56
  4. Step 4: Simplify right side
    1,261.15x = 1,216,312.51
  5. Step 5: Solve for x
    x = 1,216,312.51/1,261.15
  6. Step 6: Final answer
    x = 964.45

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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.