The mean marks of boys and …

11th Economics Measures of Central Tendency Arithmetic Mean in Statistics The mean marks (out of 100 ... STATISTICS The mean marks (out of 100) of boys and girls in an examination are 70 and 73, respectively. If the mean marks of all the students in that examination is 71, find the ratio of the number of boys to the number of girls. MEDIUM Share Study later VIDEO EXPLANATION ANSWER Let the total number of boys be x and the total number of girls br y. Let the sum of the marks of boys be a and the sum of the marks of girls be b. Mean marks of boys are =70 Mean marks of girls are =73 Therefore, ⇒ x a ​ =70 ⇒a=70x and ⇒ y b ​ =73 ⇒b=73y Now, mean marks of all the students is 71 Therfore, ⇒ x+y sum of the marks of all the students ​ =71 ⇒sum of the marks of all the students=a+b ⇒a+b=70x+73y Therefore, ⇒ x+y 70x+73y ​ =71 ⇒70x+73y=71x+71y ⇒2y=x ⇒ y x ​ = 1 2 ​ Hence the ratio is 2:1