How many pupils in the class?

[DanOh62]

Hello and thanks in advance for the help.

Question:

1. Mr. Snow has fewer than 200 snickers.
2. Mr. Snow wants to give each pupil in his class an equal number of snickers.
3. If Mr. Snow gives each pupil 2 snickers, there will be 70 snickers left over.
4. If Mr. Snow gives each pupil 4 snickers, he will need 10 more snickers.
5. How many pupils are there in the class?
6. How many snickers does Mr White have?

Formula: Am I close? Any tips, clues, URL's to finding the solution are greatly appreciated.

P=Number of Pupils
S=Number of Snickers

2P-S=70
4P-S=-10

OR would it be:
2P+70=S
S-4P=-10
​

 

[Quaid]

Question:

1. Mr. Snow has fewer than 200 snickers.
2. Mr. Snow wants to give each pupil in his class an equal number of snickers.
3. If Mr. Snow gives each pupil 2 snickers, there will be 70 snickers left over.
4. If Mr. Snow gives each pupil 4 snickers, he will need 10 more snickers.
5. How many pupils are there in the class?
6. How many snickers does Mr White have?

Formula: Am I close?

P=Number of Pupils

S=Number of Snickers

2P - S = 70

4P - S = -10

OR would it be:

2P + 70 = S

S - 4P = -10

​

Hi Dan:

In the first set of equations, the signs are incorrect on the values highlighted in red.

Your second set of equations is correct.

Cheers :cool:

 

[DanOh62]

Thanks Quaid...

I went with a slightly different formula because it seemed to make more sense.

S-2P=70 <=== Total Snickers - 2 times the number of pupils will result in 70 remaining snickers.
- S-4P=-10 <=== Total Snickers - 4 times the numver of pupils will result in a shortage of 10 snickers and some unhappy pupils.
-------------
2P=80 or P=40 <== We subtract the 2nd formula from the 1st because we can't solve the equation with S and P


S-2(40)=70
S-80=70
S-80+80=70+80
S=150

Validation:
150-2(40)=
150-80=70

150-4(40)=
150-160=-10

 

[JeffM]

I went with a slightly different formula because it seemed to make more sense.

S-2P=70 <=== Total Snickers - 2 times the number of pupils will result in 70 remaining snickers.
- S-4P=-10 <=== Total Snickers - 4 times the numver of pupils will result in a shortage of 10 snickers and some unhappy pupils.
-------------
2P=80 or P=40 <== We subtract the 2nd formula from the 1st because we can't solve the equation with S and P


S-2(40)=70
S-80=70
S-80+80=70+80
S=150

Validation:
150-2(40)=
150-80=70

150-4(40)=
150-160=-10

You start just fine by NAMING your variables clearly. Good job.

Now translate all the English statements about quantities into mathematical expressions.

(1) S < 200. This eventually turns out to be irrelevant, but you can't be sure of that yet. So write it down.

(2) S = 2P + 70 or S - 2P = 70. Good job.

(3) S + 10 = 4P or S - 4P = -10. You messed up in getting - S - 4P = - 10.

Third step is to use algebra to find the answer.

Fourth step is to check your answer.

That four step process works for every word problem. In this case, you made an error in step 2, but something odd happened in your step 3.

 

[Quaid]

Whoops, Dan, I'm an 'ol fool.

I started over, and I see that I misread a part of the exercise statement.

Give me a couple minutes to redo my work ... (sorry)

 

[Quaid]

Yes, my corrected results match yours.

150 snickers and 40 students.

I have corrected my first reply, and I deleted my second reply.

I apologize -- if I confused you. (Don't be afraid to challenge tutors, when they say something that you doubt. Tutors make mistakes, too.)

Cheers :cool: