Home / 816.88-1,128.72-643.54

Finding the Fourth Proportional to 816.88, 1,128.72 and 643.54

Calculator

Solution

The fourth proportional to 816.88, 1,128.72 and 643.54 is: 889.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    816.88 : 1,128.72 = 643.54 : x
  2. Step 2: Convert to fraction form
    816.88/1,128.72 = 643.54/x
  3. Step 3: Cross multiply
    816.88x = 1,128.72 × 643.54
  4. Step 4: Simplify right side
    816.88x = 726,376.47
  5. Step 5: Solve for x
    x = 726,376.47/816.88
  6. Step 6: Final answer
    x = 889.21

Related Problems

Find fourth proportional to 408.44, 564.36 and 321.77
Half scale
Find fourth proportional to 1,633.76, 2,257.44 and 1,287.08
Double scale
Find fourth proportional to 817.88, 1,130.10 and 644.54
Similar ratio
Find fourth proportional to 1,225.32, 1,693.08 and 965.31
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.