Home / 680.64-939.18-400.80

Finding the Fourth Proportional to 680.64, 939.18 and 400.80

Calculator

Solution

The fourth proportional to 680.64, 939.18 and 400.80 is: 553.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    680.64 : 939.18 = 400.80 : x
  2. Step 2: Convert to fraction form
    680.64/939.18 = 400.80/x
  3. Step 3: Cross multiply
    680.64x = 939.18 × 400.80
  4. Step 4: Simplify right side
    680.64x = 376,423.34
  5. Step 5: Solve for x
    x = 376,423.34/680.64
  6. Step 6: Final answer
    x = 553.04

Related Problems

Find fourth proportional to 340.32, 469.59 and 200.40
Half scale
Find fourth proportional to 1,361.28, 1,878.36 and 801.60
Double scale
Find fourth proportional to 681.64, 940.56 and 401.80
Similar ratio
Find fourth proportional to 1,020.96, 1,408.77 and 601.20
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.