The results of surveying 100 residents of a city reported that 40 read the daily morning paper, 70 read the daily evening paper & 20 read neither. How many:.1. Read at least 1 paper? 2. Read both? 3. Read exactly one daily paper?

From the data given, we can obtain the number of people reading at least 1 paper by taking the difference between the universal set and the set containing people not reading anything. The answer in 1 is 100-20 equal to 80. In 2, the answer is 40 + 70 - 80 equal to 30 people. 3. The people reading exactly one daily paper is 50 people

(40 - x) + (70 - x) + x + 20 = 100

130 - x = 100

-x = 100 - 130

-x = - 30

x = 30

read daily morning paper = 10

read the daily evening paper = 40

read both papers = 30

read neither paper = 20

how many read at least one paper : 80

read both = 30

read exactly one = 50