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Finding the Fourth Proportional to 1,538.01, 2,121.80 and 978.30

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Solution

The fourth proportional to 1,538.01, 2,121.80 and 978.30 is: 1,349.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,538.01 : 2,121.80 = 978.30 : x
  2. Step 2: Convert to fraction form
    1,538.01/2,121.80 = 978.30/x
  3. Step 3: Cross multiply
    1,538.01x = 2,121.80 × 978.30
  4. Step 4: Simplify right side
    1,538.01x = 2,075,752.05
  5. Step 5: Solve for x
    x = 2,075,752.05/1,538.01
  6. Step 6: Final answer
    x = 1,349.63

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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.