Home / 853.98-1,278.72-420

Finding the Fourth Proportional to 853.98, 1,278.72 and 420

Calculator

Solution

The fourth proportional to 853.98, 1,278.72 and 420 is: 628.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    853.98 : 1,278.72 = 420 : x
  2. Step 2: Convert to fraction form
    853.98/1,278.72 = 420/x
  3. Step 3: Cross multiply
    853.98x = 1,278.72 × 420
  4. Step 4: Simplify right side
    853.98x = 537,062.40
  5. Step 5: Solve for x
    x = 537,062.40/853.98
  6. Step 6: Final answer
    x = 628.89

Related Problems

Find fourth proportional to 426.99, 639.36 and 210
Half scale
Find fourth proportional to 1,707.96, 2,557.44 and 840
Double scale
Find fourth proportional to 854.98, 1,280.22 and 421
Similar ratio
Find fourth proportional to 1,280.97, 1,918.08 and 630
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.