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In a traffic survey, some bikes buses and cars were recorded. 70% of the vehicles were cars and 17% were buses. What percentage were bikes? Show me your work please!

Respuesta :

Answer:

13%

Step-by-step explanation:

There are three groups: bikes, buses, and cars.  The percentages of each must add up to 100%.

bikes + buses + cars = 100%

bikes + 17% + 70% = 100%

bikes + 87% = 100%

bikes = 13%

Percent is calculation of quantity per 100 quantity of other thing. The percentage of bikes out of of total surveyed vehicles was 13%

How to find the percentage from the total value?

Suppose the value of which a thing is expressed in percentage is "a'

Suppose the percent that considered thing is of "a" is b%

Then since percent shows per 100 (since cent means 100), thus we will first divide the whole part in 100 parts and then we multiply it with b so that we collect b items per 100 items(that is exactly what b per cent means).

Thus, that thing in number is

[tex]\dfrac{a}{100} \times b[/tex]

Assume that total T number of vehicles were surveyed.

Then, as it is given that 70% of the vehicles were cars and 17% were buses.

So, number of cars = [tex]\dfrac{T}{100} \times 70 = \dfrac{7 \times T}{10} = 0.7 \times T[/tex]

Similarly, the number of buses = [tex]\dfrac{T}{100} \times 17 = 0.17 \times T[/tex]

Thus, number of bikes = Total vehicles - number of cars and buses

Number of bikes = T - 0.7T - 0.17T = T(1 - 0.87) = 0.13T

Taking its percentage with total vehicles, let it be x% of total vehicles, then

[tex]0.13T = \dfrac{T}{100} \times x\\\\\text{Multiplying 100/T on both the sides}\\\\13 = x\\x = 13[/tex]

(we could have used short cut that total there is 100%, since number of  cars = 70% of total, number of buses = 17% of total, thus

total vehicle's percent being bike = all vehicle (100%) - percent of cars - percent of buses) = (100 - 70 -17)% = 13% )

Thus, the percentage of bikes out of of total surveyed vehicles was 13%

Learn more about percentage here:

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