Home / 871.11-1,305.75-639.65

Finding the Fourth Proportional to 871.11, 1,305.75 and 639.65

Calculator

Solution

The fourth proportional to 871.11, 1,305.75 and 639.65 is: 958.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    871.11 : 1,305.75 = 639.65 : x
  2. Step 2: Convert to fraction form
    871.11/1,305.75 = 639.65/x
  3. Step 3: Cross multiply
    871.11x = 1,305.75 × 639.65
  4. Step 4: Simplify right side
    871.11x = 835,222.99
  5. Step 5: Solve for x
    x = 835,222.99/871.11
  6. Step 6: Final answer
    x = 958.80

Related Problems

Find fourth proportional to 435.56, 652.88 and 319.83
Half scale
Find fourth proportional to 1,742.22, 2,611.50 and 1,279.30
Double scale
Find fourth proportional to 872.11, 1,307.25 and 640.65
Similar ratio
Find fourth proportional to 1,306.67, 1,958.63 and 959.48
1.5x scale

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.