Question

9.
The average marks of 15 students in a class is 145, maximum marks being 150. If the two lowest scores are remove
the average increases by 5. Also the two lowest scores are consecutive multiple of 9. Find out the lowest score in e
class.
(b) 117
(a) 126
(d) None of these
(c) 108
​

Answer 1

Answer:

$\text{The lowest score is}108$

$\text{option (c) is correct }$

Step-by-step explanation:

$\text{Given:}$

$\text{Average mark of 15 students is 145}$

$\therefore\text{Total marks of the claas=15*145=2175}$

$\text{Let the two lowest scores be 9x, 9(x+1)}$

when the two lowest scores are removed, the total marks of the class becomes 2175-(9x+9(x+1))

$\text{Now,}$

$\text{New average=150}$

$\frac{\Sigma{x}}{n}=150$

$\frac{2175-(9x+9(x+1))}{13}=150$

$\implies\:\frac{2175-(18x+9)}{13}=150$

$\implies\:2175-(18x+9)=1950$

$\implies\:2166-18x=1950$

$\implies\:2166-1950=18x$

$\implies\:216=18x$

$\implies\:x=12$

$\text{The lowest score is}=9x=9*12=108$