Simple Math questions I don't get

[suigeneris]

Hi everyone, I don't understand this question, lol. If anyone here could shed some light, I'd be very thankful. What kind of problem are these, and what's the proper method of solving them?

Well, there's 2 questions I don't understand. I'm studying Math for my GED test.

1.) An 18m path is being built using a nail every 25cm. What's the ratio of the number of nails to the number of metres of path?

2.) A map scale shows that 1/3 cm on the map = an actual distance of 3 km. If a distance on the map is 3/4 cm, what is the actual distance in kilometres?

Yes.... I'm fairly bad at Math lol!

Thank you.

 

[daon2]

Hi everyone, I don't understand this question, lol. If anyone here could shed some light, I'd be very thankful. What kind of problem are these, and what's the proper method of solving them?

Well, there's 2 questions I don't understand. I'm studying Math for my GED test.

1.) An 18m path is being built using a nail every 25cm. What's the ratio of the number of nails to the number of metres of path?

1 nail every 25cm is the same as how many nails every 1m? Think: how many centimeters are there in a meter?

2.) A map scale shows that 1/3 cm on the map = an actual distance of 3 km. If a distance on the map is 3/4 cm, what is the actual distance in kilometres?

Yes.... I'm fairly bad at Math lol!

Thank you.

Every 1/3 of a centimeter on the map is 3km in real life. So 1cm = (1/3)cm + (1/3)cm + (1/3)cm is 9km in real life.

Now if you have x centimeters, it's the same as 9*x km.

 

[HallsofIvy]

Hi everyone, I don't understand this question, lol. If anyone here could shed some light, I'd be very thankful. What kind of problem are these, and what's the proper method of solving them?

Well, there's 2 questions I don't understand. I'm studying Math for my GED test.

1.) An 18m path is being built using a nail every 25cm. What's the ratio of the number of nails to the number of metres of path?

What's the ratio of 25 cm to 1 m? (How many centimeters are there in a meter?)

2.) A map scale shows that 1/3 cm on the map = an actual distance of 3 km. If a distance on the map is 3/4 cm, what is the actual distance in kilometres? [/quote]
Set it up as a proportion: the ratio of 3 km to 1/3 cm (actual to map) is
\(\displaystyle \frac{3}{\frac{1}{3}}= 9\). Calling the actual distance "x", the ratio of "actual to map" is \(\displaystyle \frac{x}{\frac{3}{4}}\). The proportion is \(\displaystyle \frac{x}{\frac{3}{4}}= 9\). Solve for x by multiplying both sides by \(\displaystyle \frac{3}{4}\).

Yes.... I'm fairly bad at Math lol!

Thank you.

 

[pphani]

1.) An 18m path is being built using a nail every 25cm. What's the ratio of the number of nails to the number of metres of path?

One nail is used for every 25cm. Here they asked you to find a ratio between number of nails to number of meters.

We already have number of meters i.e. nothing but path = 18m

We need to find number of nails used to build 18m path.

1 meter = 100 cm

Here, one nail is used for every 25cm. Therefore, 4 nails are used to build 1m path.

To build 18m path, we need to use 4*18 = 72. So 72 nails are used to build 18m path.

Therefore ratio = Number of nails used / path = 72/18 = 4 :1

 

[HallsofIvy]

1.) An 18m path is being built using a nail every 25cm. What's the ratio of the number of nails to the number of metres of path?

One nail is used for every 25cm. Here they asked you to find a ratio between number of nails to number of meters.

We already have number of meters i.e. nothing but path = 18m

We need to find number of nails used to build 18m path.

1 meter = 100 cm

Here, one nail is used for every 25cm. Therefore, 4 nails are used to build 1m path.

To build 18m path, we need to use 4*18 = 72. So 72 nails are used to build 18m path.

This is incorrect because you are taking one nail at the end of a meter and one nail at the beginning of a meter when, in fact, they are the same nail. Instead calculate 3 nails per meter and add 1 for the initial nail.
3(18)+ 1= 54+ 1= 55 nails, not 72.

Therefore ratio = Number of nails used / path = 72/18 = 4 :1