Question 636283: 3 times the square of a certain positve number exceeds 6 times the number by 9. Find d number.
In a certain company, 30% of the men & 20% of the women attend night sch. If 40% of all employees are men, what % of all the employees attend night school?
If a boat goes downstream 72 miles in 3 hrs & upstream 60 miles in 6 hrs, the rate of the river & the rate of the boat in still water respectively are?
Answer by sachi(548)   (Show Source):
You can put this solution on YOUR website! A)3 times the square of a certain positve number exceeds 6 times the number by 9. Find d number.
ans:-
let the no is x
as per question 3x^2=6x+9
or 3x^2-6x-9=0
or 3x^2+3x-9x-9=0
or 3x(x+1)-9(x=1)=0
or (3x-9)(x+1)=0
or x=3 or -1 ans
B)In a certain company, 30% of the men & 20% of the women attend night sch. If 40% of all employees are men, what % of all the employees attend night school?
ans:
let there are x no of employees
out of that men=40%=0.4x
so clearly women =0.6x
30% of the men & 20% of the women attend night sch
so total employee attend night shift=0.3*0.4x+0.2*0.6x=0.24x
so the % employee attend night shift=(0.24x/x)*100=24% ans
C)If a boat goes downstream 72 miles in 3 hrs & upstream 60 miles in 6 hrs, the rate of the river & the rate of the boat in still water respectively are?
ans:-
let the speed of boat = u mile/hr & that of strem=v mile/hr
so the speed in down stream=u+v & in up stream=u-v
as per question
3(u+v)=72 =>u+v=24 ----1
6(u-v)=60=u-v=10 -----2
by solving avove eqns
u the speed of boat=17 miles/hr & that of stream=7 miles/hr ans
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