F.2maths~~

1.The scale of the plan of a flat is 1:300 . On the plan , a rectangular room
measures 3.2cm long and 2.6cm wide . Find the ratio of the area of the room
on the plan to its actual area .
the required ratio=(3.2x2.6)/(3.2x300x2.6x300)=1:90000

2.In a school , the number of boy scouts and that of girl guides are in the ratio 3:5 . If there are 8 more girl guides than boy scouts , find the total number of boy scouts and girl guides in the school .
Let total number of boy scouts be x, girl guides be y
x:y=3:5---(1)
y-x=8---(2)
(2), y=8+x----(3)
Thus, x/(8+x)=3/5
5x=3(8+x)
5x=24+3x
2x=24
x=12
y=8+12=20
So, the total number of girl guides are 20 and the boys are 12


3.The time taken by a train to go from station A to station B is 3 mins 49 s .
Express this time in
(a)min , correct to 2 sig fig
3mins49s=3+49/60(mins)=3.8mins(correct to 2 sig fig)
(b)seconds , correct to 2 sig fig
3mins49s=3x60+49=229=230(correct to 2sig fig)