# Yr 7 Maths

#### Ssequeira

##### New member
As per attached PLEASE explain Q 12 n 15

Thanking you

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#### JeffM

##### Elite Member
You said in your prior post that your son is 6. These are not math questions for a 6 year old. These are questions for someone who has had 6 years of arithmetic.

#### Dr.Peterson

##### Elite Member
As per attached PLEASE explain Q 12 n 15

Thanking you
Does "n" mean "and"? It's not a good idea to abbreviate in a math question, because every letter has a potential meaning!

But before I try to help, I'd like to have a better idea what kind of help is needed, so please show us what you/your son do understand about it, and make an attempt to solve the problems. See this summary of guidelines for submission.

In particular, is there a reason these two problems give you trouble, but others (which are similar) don't?

#### Ssequeira

##### New member
You said in your prior post that your son is 6. These are not math questions for a 6 year old. These are questions for someone who has had 6 years of arithmetic.
Hi My son is 6 but he is studying for 7 year entrance test, attached is a page from the book, which prepares the student for entrance exam

#### Ssequeira

##### New member
Yr7 Math

Does "n" mean "and"? It's not a good idea to abbreviate in a math question, because every letter has a potential meaning!

But before I try to help, I'd like to have a better idea what kind of help is needed, so please show us what you/your son do understand about it, and make an attempt to solve the problems. See this summary of guidelines for submission.

In particular, is there a reason these two problems give you trouble, but others (which are similar) don't?
Thanks for taking time to read. I was meaning please help explain Question 12 and Question 15 from the book ( I have the answer in the book, but I don't have detail explanation

#### Otis

##### Senior Member
In question 12, they want the given fraction expressed as a percent.

For example, what percent of pizzas are delivered hot, if 5/8ths of the pizzas are delivered hot?

5 ÷ 8 × 100 = 62.5%

In question 15, they've given the scale ratio as $$\displaystyle \dfrac{1 \text{unit model length}}{200 \text{unit real length}}$$

So any ratio of lengths model/real must equal 1/200. For example, if the model casts a shadow that is 3 cm long, then we could set up a proportion to find how long the real shadow would be.

$$\displaystyle \dfrac{3}{?} = \dfrac{1}{200}$$

One way to solve a proportion for the unknown part is to: (1) multiply on the diagonal and (2) divide by the number not used.

3 × 200 ÷ 1 = 600

The real shadow is 600cm long (6m).

Because the numerator in 1/200 is one, we can say that every real length is 200 times larger than its modeled length. :cool:

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#### Ssequeira

##### New member
Yr 7 maths

In question 12, they want the given fraction expressed as a percent.

For example, what percent of pizzas are delivered hot, if 5/8ths of the pizzas are delivered hot?

5 ÷ 8 × 100 = 62.5%

In question 15, they've given the scale ratio as $$\displaystyle \dfrac{1 \text{unit model length}}{200 \text{unit real length}}$$

So any ratio of lengths model/real must equal 1/200. For example, if the model casts a shadow that is 3 cm long, then we would set up a proportion (i.e., two equal ratios) to find how long the real shadow would be.

$$\displaystyle \dfrac{3}{?} = \dfrac{1}{200}$$

One way to solve a proportion for the unknown part is to: (1) multiply on the diagonal and (2) divide by the number not used.

3 × 200 ÷ 1 = 600

The real shadow is 600cm long (6m).
Thanks a lot for your help