Home / 491.68-678.43-305.20

Finding the Fourth Proportional to 491.68, 678.43 and 305.20

Calculator

Solution

The fourth proportional to 491.68, 678.43 and 305.20 is: 421.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    491.68 : 678.43 = 305.20 : x
  2. Step 2: Convert to fraction form
    491.68/678.43 = 305.20/x
  3. Step 3: Cross multiply
    491.68x = 678.43 × 305.20
  4. Step 4: Simplify right side
    491.68x = 207,056.84
  5. Step 5: Solve for x
    x = 207,056.84/491.68
  6. Step 6: Final answer
    x = 421.12

Related Problems

Find fourth proportional to 245.84, 339.22 and 152.60
Half scale
Find fourth proportional to 983.36, 1,356.86 and 610.40
Double scale
Find fourth proportional to 492.68, 679.81 and 306.20
Similar ratio
Find fourth proportional to 737.52, 1,017.65 and 457.80
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.