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The pie chart below has the breakup of the number of students from different departments in an engineering college for the year $2012$. The proportion of male to female students in each department is $5:4$. There are $40$ males in Electrical Engineering. What is the difference between the numbers of female students in the civil department and the female students in the Mechanical department?

edited | 2.5k views

Number of female students in Electrical = $40\times \dfrac{4}{5} = 32$

Number of female students in Civil = $32\times \dfrac{30}{20} = 48$ (Since proportion of male students to female students is same, the breakup chart is the same for number of female students)

Number of female students in Mechanical = $32\times \dfrac{10}{20} = 16$

So, answer = $48 - 16 = 32$
by Veteran (431k points)
edited
+1
Why divide by 20 while finding number of female students in civil and mechanical?
Electrical male students = 40
∴ Electrical female students = 40 × (4/5)= 32
Total no. of students in Electrical department = (40 + 32) = 72 (which is 20% of the total mass)
∴ Total no. of students in the college = 72 × (100/20) = 360
Total no. of students in Civil department = 360 × (30/100) = 108
Civil female students = 108 × (4/9) = 48
Total no. of students in Mechanical department = 360 × (10/100) = 36
Mechanical female students = 36 × (4/9) = 16
∴ Difference = (48 − 16) = 32 (Ans)
by Active (1k points)
0
nice ..
0
Good explanation