Miscellaneous skills on rate.
1. An aeroplane flies 1 215 km from hong kong to shanghai in 2.5 hours.
(a) Find the speed of the aeroplane in km/h
(b) the aeroplane then flies 1 076 km from Shanghai to beijing at the same speed obtained above. find the tim taken for this flight, correct to the nearest 0.1 hour.
2.A car runs 180 km in 2.5 hours
(a) If its speed is decreased by 2 km/h,find the distance in km that it will travel in 4分之3 hour.
(b) If its speed is increased by 2m/s,find the distance in km that it will travel in 90 minutes.
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2012-11-28 6:00 am
回答 (2)
2012-11-28 6:15 am
✔ 最佳答案
1(a) The speed of the aeroplane = 1215/2.5
= 486 km/h
(b) Time from Shanghai to beijing
= 1076/486
= 2.2 hours (correct to the nearest 0.1 hour)
(a) The original speed is 180/2.5 = 72
So, it will travel 70 * 1.75 = 122.5 km after decrease the speed by 2 km/h
(b) 2m/s = 2 * 3600 km /1000 * 1 h = 7.2 km/h
So, it will travel 79.2 * 1.5 = 118.8 km after increase the speed by 2 m/s
2012-11-28 6:15 am
1.
(a)
Required answer
= 1215 / 2.5
= 486 km/h
(b)
Required answer
= 1076 / 486
= 2.2 hours (correct to the nearest 0.1 hour)
2.
(a)
Original speed
= 180 / 2.5
= 72 km/h ... (i)
New speed
= 72 - 2 ... By (i)
= 70 km/h
Requied answer
= 70 x 3/4
= 52.5 km
(b)
2 m/s
= 2(3600/1000) km/h
= 7.2 km/h
New speed
= 72 + 7.2 ... By (i)
= 79.2 km/h
Required answer
= 79.2 x 90/60
= 118.8 km/h
(a)
Required answer
= 1215 / 2.5
= 486 km/h
(b)
Required answer
= 1076 / 486
= 2.2 hours (correct to the nearest 0.1 hour)
2.
(a)
Original speed
= 180 / 2.5
= 72 km/h ... (i)
New speed
= 72 - 2 ... By (i)
= 70 km/h
Requied answer
= 70 x 3/4
= 52.5 km
(b)
2 m/s
= 2(3600/1000) km/h
= 7.2 km/h
New speed
= 72 + 7.2 ... By (i)
= 79.2 km/h
Required answer
= 79.2 x 90/60
= 118.8 km/h
參考: Myself
收錄日期: 2021-04-27 17:46:02
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