Maths Made Easy › Forums › Standard › Rates & Ratios › Rates
Tagged: percentage gain, Rates

AuthorPosts

Goods costing 35c per kg are sold at $420 per tonne. Find the gain as percentage of the cost price. 35c/kg = $0.35/kg 0.35 × 1000 = $350/tonne first we must convert to same units 1000kg = 1 tonne gain = 420 – 350 = $70 find the gain = ^{70}/_{350} × 100 = 20% to change to percentage gain = ^{gain}/_{original price} × 100 
If the Earth travels through space at a speed of 106,000km/h then the distance travelled by the Earth (in metres) in 30 days in scientific notation is? 106,000 × 24 × 30
= 76,320,000Distance = speed × time
speed = 106,000
time = 30 days which is 30 × 24 hours= 76,320,000 × 1000
= 76,320,000,000mto convert to metres we times the km by 1000 = 7.632 × 10^{10} m to convert to scientific notation, we need to move the decimal from the end to in between the 7 and the 6, which is 10 places, hence will be 7.632 times 10 to the power of 10 total mass = 42 + 12 + 6
= 60kgfind the total weight by adding water, protein and bone 
A liquid fertilizer is diluted at a rate of 15ml per 10 litres of water. The label claims that 5L of diluted mixture is required per every 10 square metres of lawn. How many ml of fertilizer is needed to fertilize a 120m^{2} lawn? 120 ÷ 10 = 12 first we find out how many 10 metres squared are in 120 metres squared by dividing total amount of litres of mixture = 12 × 5
= 60 Litresso we need 12 lots of 5 Litres
which is 60 Litres of mixture60 ÷ 10 = 6 each 10 litres of mixture has 15mls of fertilizer in, so we find out how many lots of 10L is in 60L by dividing 6 × 15 = 90ml we need 6 lots of the fertilizer : which is 6 lots of 15ml 
Water flows from an irrigation pipe at the rate of 2.4m^{3} every minute. How long would it take for 100 litres of water to flow from the pipe? (1000L = 1m^{3})?
2.4 × 1000
= 2400L convert 2.4m^{3} into litres by multiplying by 1000
2400L per minute flows through this pipe
100 ÷ 2400
= 0.0416 minutes to find how long it takes for 100L to flow, divide by 2400 as this gives us 0.0416 minutes 0.0416 × 60
= 2.5 secs convert to seconds by multiplying by 60
[br] 
A drop of water contains about 1.7 × 10^{21} molecules. A typical waterfall may have a flow of 7.5 × 10^{11} drops of water per minute. How many molecules of water flow over the waterfall in one minute?
1.7 × 10^{21} × 7.5 × 10^{11 }
= 1.275 × 10^{33} 
A tap runs at 9L of water per minute. If you leave the tap on while brushing your teeth for 4.5 minutes each day, how much water would be used in a week brushing your teeth? = 4.5 × 7 = 31.5 minutes per week
there are 7 days in a week, so find out the total amount of minutes in the week that the water is used total water = 31.5 × 9 = 283.5L
each minute uses 9L, so multiply the 9L by 31.5 minute 
The average NSW annual water consumption from the residential sector is equal to 90 340 litres per person per year. The Building Sustainability Index (BASIX) uses this as the benchmark to set a target for reducing water consumption by up to 40%. A new building, planned to house 50 people, has been designed to meet a 25% reduction on this water consumption benchmark. How much water per year, to the nearest kilolitre, is this building designed to save when fully occupied? 90 340 × 50 =4 517 000 L each person uses 90 340L a year and there will be 50 people , multiply to find the number of litres for all the people 4 517 000 × 25% = 1 129 250L find 25% of the total amount of litres 1 129 250 ÷ 1000 = 1129.25 KL convert to kilolitres by dividing by 1000 as 1KL = 1000L = 1129KL round to nearest KL 
A piece of meat weighing 1kg needs to be cooked for one hour. How many hours and minutes would you need to cook a piece of meat weighing 2.6kg?
For every kg, need 1 hour
2.6 × 1 = 2.6hours
convert to hours and minutes using the degrees, minutes, seconds button on your calculator (° ‘ “)
= 2h 36 minutes 
AuthorPosts
You must be logged in to reply to this topic.