Home / 642.88-881.39-631.21

Finding the Fourth Proportional to 642.88, 881.39 and 631.21

Calculator

Solution

The fourth proportional to 642.88, 881.39 and 631.21 is: 865.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.88 : 881.39 = 631.21 : x
  2. Step 2: Convert to fraction form
    642.88/881.39 = 631.21/x
  3. Step 3: Cross multiply
    642.88x = 881.39 × 631.21
  4. Step 4: Simplify right side
    642.88x = 556,342.18
  5. Step 5: Solve for x
    x = 556,342.18/642.88
  6. Step 6: Final answer
    x = 865.39

Related Problems

Find fourth proportional to 321.44, 440.70 and 315.61
Half scale
Find fourth proportional to 1,285.76, 1,762.78 and 1,262.42
Double scale
Find fourth proportional to 643.88, 882.76 and 632.21
Similar ratio
Find fourth proportional to 964.32, 1,322.09 and 946.82
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.