Lower Secondary Mathematics

[ChewingPencilLine]

Question (2)


12 pounds of peanuts would cost 12 * $3 = $36
Let the number of pounds of cashews mixed in be represented by x.

Given the price of the cashews and peanuts, it can be calculated that the total price of the mixture is given by
(x * $6) + $36 = $(6x + 36) ---------- (1)

Given the total weight of the mixture (x + 12) pounds, it can be calculated that the total price of the mixture is given by
$4.2 * (x + 12) = $(4.2x + 50.4) --------- (2)

This is a set of simultaneous linear equations, which a Secondary 1 student should be able to solve easily:

6x + 36 = 4.2x + 50.4
1.8x = 14.4
x = 8

Recall that x stands for the number of pounds of cashew nuts to be mixed in.
Therefore, the answer is 8 pounds.

[ChewingPencilLine]

Question 3


Let x be the time at which Steven met Jason in minutes, after the 3 of them started walking from Town A to B or B to A respectively.

in x minutes, Steven would have walked 100x meters.
in x minutes, Jason would have walked 80x meters.

Since Steven and Jason must have met some point in between town A and town B, we know that the distance between Town A and Town B is given by
100x + 80x = 180x ----------- (1)

in x + 6 minutes, Steven would have walked 100 (x+6) = 100x + 600 meters.
in x + 6 minutes, Melvin would have walked 75 (x+6) = 75x + 450 meters.

Since Steven and Melvin must have met some point in between town A and town B, we know that the distance between Town A and Town B is given by
100x + 600 + 75x + 450 = 175x + 1050 ----------- (2)

Equating the 2 equations, you get
180x = 175x + 1050
5x = 1050
x = 210

Recall that the total distance between town A and town B is given by 180x (equation 1).
Therefore, 180 * 210 = 37800 meters = 37.8 km

[ChewingPencilLine]

The key is to read the question and understand what x should be used to stand for. A lot of the times, x is used to stand for the quantity you are looking for. For example, look at question 2. I used x to stand for the amount of cashew nuts to be mixed in, in pounds.


However, this is not always the case. Try to think and see what quantity x should represent to simplify the question. For example, in question 3, it is obvious that the common quantity between scenario 1 (Steven meeting Jason) and scenario 2 (Steven meeting Melvin) is the time at which Steven passed Jason (they tell you that Steven met Melvin 6 mins after passing Jason!).

Hope I have helped some!

[PuffyCakes]

Thx alot kind souls<3

[ChewingPencilLine]

Haha, no problem. And it is just one soul Me!

[PuffyCakes]

U helped me alot:)

[mathtuition88]

Dear Parents,

Many parents have feedback to me that their child often makes careless mistakes in Maths, at all levels, from Primary, Secondary, to JC Level.

How to avoid Careless Mistakes for Maths?

Please read my article, which includes some suggestions and tips.

http://mathtuition88.wordpress.com/singapore-math-tuition-blog/

[Augs]

Hi. Does anyone know of any good Sec 1NA Maths assessment book? I prefer it to go topic by topic, instead of in exam papers format. I went to Lot One popular and could only find 2 types of Maths assessment books for Sec 1 NA, and both are in exam papers format. Any recommendation on which assessment books and which outlet to get?

[Augs]

Hi. Does anyone know of any good Sec 1NA Maths assessment book? I prefer it to go topic by topic, instead of in exam papers format. I went to Lot One popular and could only find 2 types of Maths assessment books for Sec 1 NA, and both are in exam papers format. Any recommendation on which assessment books and which outlet to get?

[mummy so kiasu]

Augs:

Hi. Does anyone know of any good Sec 1NA Maths assessment book? I prefer it to go topic by topic, instead of in exam papers format. I went to Lot One popular and could only find 2 types of Maths assessment books for Sec 1 NA, and both are in exam papers format. Any recommendation on which assessment books and which outlet to get?

Have you try asking the popular staff to recommend?