If the average price of four pairs of shoes is $50, and three of those pairs of shoes are priced at $35, $40 and $55, what is the price of the fourth pair of shoes?

The average price is calculated by dividing the sum of all prices with the number of items.

average price = price1+price2 + ... priceN/N

In our case, we have four pairs of shoes. So, N=4.

We also know the average price. average price=$50

We also know the price of the first pair of shoes (price1), of the second (price2) and the third (price3). We need to find out Price4:

$50=$35+$40+$55+Price4/4

50*4 = $35+$40+$55+Price4

$200=$130+Price4

Price4=200-130

Price4=$70