rawan
عدد المساهمات : 45 العمر : 24 العمل/الترفيه : طالب فصل : 1/6 prep المزاج : good مزاجي اليوم : المهنة : الهواية : نقاط : 21801 السٌّمعَة : 0 تاريخ التسجيل : 14/05/2009
| موضوع: Distance, rate and time الأحد سبتمبر 12, 2010 6:19 pm | |
| A rate is a ratio that compares two different kinds of numbers, such as miles per hour or dollars per pound. A unit rate compares a quantity to its unit of measure. A unit price is a rate comparing the price of an item to its unit of measure.
The rate "miles per hour" gives distance traveled per unit of time. Problems using this type of rate can be solved using a proportion, or a formu
:lRate is a very important type of ratio, used in many everyday problems, such as grocery shopping, traveling, medicine--in fact, almost every activity involves some type of rate. Miles per hour or feet per second are both rates of speed. Number of heartbeats per minute is called "heart rate." If you ask a babysitter, "What is your rate?", you are asking how many dollars per hour you will be charged. The little word "per" is always a clue that you are dealing with a rate. Unit price is a particular rate that compares a price to some unit of measure. For example, suppose eggs are on sale for $.72 per dozen. The unit price is $.72 divided by 12, or 6 cents per egg.
The word "per" can be replaced by the "/" in problems, so 6 cents per egg can also be written 6 cents/egg.
Smart shoppers know how to estimate unit prices when deciding whether it's better to buy a larger size of an item. Many everyday problems involve rates of speed, using distance and time. We can solve these problems using proportions and cross products. However, it's easier to use a handy formula: rate equals distance divided by time: r = d/t. Actually, this formula comes directly from the proportion calculation -- it's just that one multiplication step has already been done for you, so it's a shortcut to learn the formula and use it. You can write this formula in two other ways, to solve for distance (d = rt) or time (t = d/r).
Examples Let's say you rode your bike 2 hours and traveled 24 miles. What is your rate of speed? Use the formula r = d/t. Your rate is 24 miles divided by 2 hours, so:
r = 24 miles ÷ 2 hours = 12 miles per hour.
Now let's say you rode your bike at a rate of 10 miles per hour for 4 hours. How many miles did you travel? This time, use the distance formula d = rt:
d = 10 miles per hour × 4 hours = 40 miles.
Next, you ride 18 miles and travel at a rate of 12 miles per hour. How long did this take you? Use the time formula t = d/r:
t = 18 miles ÷ 12 miles per hour = 1.5 hours, or 1 ½ hours
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سارة أيمن Admin
عدد المساهمات : 5871 العمر : 27 الموقع : -------------- العمل/الترفيه : طالبة فصل : :'( المزاج : disappointed مزاجي اليوم : المهنة : الهواية : أوسمة العضو : نقاط : 30416 السٌّمعَة : 201 تاريخ التسجيل : 06/12/2008
| موضوع: رد: Distance, rate and time الأحد سبتمبر 12, 2010 10:10 pm | |
| Nice Topic Rawan ^_^ waitinh 4 more thnxxxxxxxx | |
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hadeer hany مشرف فعال
عدد المساهمات : 856 العمر : 24 الموقع : http://zohor-mostaqble.ahlamontada.com العمل/الترفيه : طالبة المزاج : HAPPY مزاجي اليوم : المهنة : الهواية : أوسمة العضو : نقاط : 23130 السٌّمعَة : 14 تاريخ التسجيل : 02/04/2009
| موضوع: رد: Distance, rate and time الأحد سبتمبر 12, 2010 11:59 pm | |
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