Math F.1(Ratio and Rate)

Math F.1(Ratio and Rate)

1.A wheel rotates 15 turns to travel a distance of 27 m .Find the nuber of rotat

ions for travelling 405m.

the wheel rotates of 1 turns:

27÷15

=1.8m/turns

求1個wheel rotates first,

then you can know 1 turn of wheel rotatess

可以知道 a wheel rotates for 1 turn is 1.8 m/turn

the number of rotation for travelling 405 m:

405÷1.8

=225turns

題目話405米可轉多少圈


知道A wheel rotates for 1 turn is 1.8,

405÷1.8

便知道答案。


2) Anne typed 1000 words at a speed of 30 words/min, and then typed 750 wo

rds at a speed of 40 words/min.Find her average typing speed

ime used :

= 1000/30 750/40

average typing speed:

= (1000 750)÷(1000/30 750/40)

= 33.6 words/min



* remember

when you find average speed,

you should use this formula

average speed = distrance÷time, in chinese

=平均速率=距離÷時間

第二題重點就系上面那條公式,背熟佢,很有用!!!

1) A wheel rotates 15 turns to travel a distance of 27 m .Find the nuber of rotations for travelling 405m.
(405)(15)/27 = 225 turns
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2) Anne typed 1000 words at a speed of 30 words/min, and then typed 750 words at a speed of 40 words/min.Find her average typing speed.
time used = 1000/30 + 750/40
average typing speed = (1000 + 750) / (1000/30 + 750/40) = 33.6 words/min