In the faculty of Reverse-Engineering, 226 second year students study numeric methods, 423 second year students study automatic control of airborne vehicles and 134 second year students study them both. How many students are there in the faculty if the second year students are approximately 90% of the total?  Choose the correct choice from the following answers:
A) 515.
B) 572.
C) 618.
D) 644.
E) 666.
Answer is B :572   Solution : Total number of students studying both are 423 + 226 - 134= 
<gadget id="calculator">423 + 226 - 134</gadget>
<output>515</output>
515 (Subtracting the 134 since they were included in the both the other numbers already).   So 90% of total is 515, so 100% is approx. 572.
<result>B</result>
In the faculty of Reverse-Engineering, 226 second year students study numeric methods, 423 second year students study automatic control of airborne vehicles and 134 second year students study them both. How many students are there in the faculty if the second year students are approximately 90% of the total?