In a group of people, $12$ people know music, $15$ people know drawing and $7$ people know both music and drawing. If people know either music or drawing then calculate the number of people in the group.

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Solution

$n (M) = 12, n (D) = 15, n (M \cap D) = 7 n (M \cup D = ?$
$n (M) + n (D) = n (M \cup D) + n (M \cap D)$
OR
$n (M \cup D) = n (M) + n (D) - n (M \cap D)$
$= 12 + 15 - 7$
$= 27 - 7$
$n (M \cup D) = 20$
Number of people in the group $= 20$

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In a group of people, 12 people know music, 15 people know drawing and 7 people know both music and drawing. If people know either music or drawing then calculate the number of people in the group.

n(M)=12, n(D)=15, n(M∩D)=7 n(M∪D=?n(M)+n(D)=n(M∪D)+n(M∩D)ORn(M∪D)=n(M)+n(D)−n(M∩D)=12+15−7=27−7n(M∪D)=20Number of people in the group =20

In a group of people, $12$ people know music, $15$ people know drawing and $7$ people know both music and drawing. If people know either music or drawing then calculate the number of people in the group.

$n (M) = 12, n (D) = 15, n (M \cap D) = 7 n (M \cup D = ?$
$n (M) + n (D) = n (M \cup D) + n (M \cap D)$
OR
$n (M \cup D) = n (M) + n (D) - n (M \cap D)$
$= 12 + 15 - 7$
$= 27 - 7$
$n (M \cup D) = 20$
Number of people in the group $= 20$