Q&A - P5 Math

[tianzhu]

anneshirleygilbert:

Can somebody please help with this question?

There are 85 plates of fried noodles for 80 people. Each adult eats 2 plates of fried noodles and every 3 children share 1 plate of fried noodles. How many adults and how many children are there? (Ans given is: 35 adults and 45 children)

Hi

You may use a strategy called “Make a Supposition”.

This question is similar to the familiar ‘Counting heads and legs” type but given a slight tweak.

Suppose there were 80 adults.

80*2 ------ 160

Now increase a group of 3 children, hence you’ll have 77 adults to make a total of 80 people.

(77*2) + 1 ------ 155.

For every increase of 3 children, we see a reduction of 5 plates of fried noodles (160 - 155)

160 – 85 ------ 75

75/5 ----- 15

For a reduction of 75 plates, you have to reduce the number of children by 15 groups of 3.

Hence (15*3) or 45 chilldren.

80 - 45 ------ 35 (adults)

Best wishes

[anneshirleygilbert]

Thank you, tianzhu. You have explained it very clearly and methodically. Shall show it to my daughter when she returns from school.

[Winx5015]

Hi, need help for the following questions.


Q1). The total number of sheep in Farm A and Farm B was 980. After 60% of the sheep in Farm A and 200 of the sheep in Farm B were sold, the ratio of the number of sheep left in Farm A to Farm B became 1:4. Find the total number of sheep left in Farm A and Farm B.

Q2). Steve baked some cookies. If he give 4 cookies to his friends, he would have 2 cookies left over. If he give 5 cookies to his friends, he would be short of 2 cookies. What is the least number of friends Steve have?

Q3). There are 648 turkeys, goats and ducks in a farm. The ratio of the number of turkeys to the total number of goats and ducks is 5:7. The ratio of the number of goats to the number of turkeys and ducks is 3:5. Find the ratio of the turkeys to the goats to the ducks.

Thanks!

[Winx5015]

Hi MathIzzzFun,


Just for your info, the answer for my question 2 (about the bags and belts) in which I posted on 12 Oct 2011 is not 13. Still don't have the correct answer for this question.

:scratchhead:

[MathIzzzFun]

Winx5015:

Hi MathIzzzFun,


Just for your info, the answer for my question 2 (about the bags and belts) in which I posted on 12 Oct 2011 is not 13. Still don't have the correct answer for this question.

:scratchhead:

hi

Sue has some money. She spends $100 on 3 identical bags and 7 identical belts. If she wants to buy another bag, she will be short of $4. However, if she buys 1 more belt, she will have $6 left. How much money does Sue has?

The question ask \"How much does Sue have?\" so it has to be amount left over...

If the question is \"How much did Sue have ?\" then the answer is --> $100 spent + $13 left = $113

cheers.

[MathIzzzFun]

Winx5015:

Hi, need help for the following questions.


Q1). The total number of sheep in Farm A and Farm B was 980. After 60% of the sheep in Farm A and 200 of the sheep in Farm B were sold, the ratio of the number of sheep left in Farm A to Farm B became 1:4. Find the total number of sheep left in Farm A and Farm B.

Thanks!

Hi

work backwards..

Left --> Farm A : Farm B = 1: 4 = 4u : 16u
Before the sheep were sold,
Farm A = 10u
Farm B = 16u + 200

10u + 16u + 200 = 980, 26u = 780, 1u = 30

Farm A, sheep left = 4u = 120
Farm B, sheep left = 16u = 480

cheers.

[MathIzzzFun]

Winx5015:

Hi, need help for the following questions.


Q2). Steve baked some cookies. If he give 4 cookies to his friends, he would have 2 cookies left over. If he give 5 cookies to his friends, he would be short of 2 cookies. What is the least number of friends Steve have?

Thanks!

Hi

Assume 4 cookies given to each of his friend and he had 2 cookies left. Now, in order for each of the friend to have 5 cookies, he had to give 1 more to each.

Since he will be short of 2 cookies, number of friends = 2 + 2 = 4

cheers.

[MathIzzzFun]

Winx5015:

Hi, need help for the following questions.


Q3). There are 648 turkeys, goats and ducks in a farm. The ratio of the number of turkeys to the total number of goats and ducks is 5:7. The ratio of the number of goats to the number of turkeys and ducks is 3:5. Find the ratio of the turkeys to the goats to the ducks.

Thanks!

Hi

turkeys : goats + ducks = 5:7
turkeys : turkeys + goats + ducks = 5 : 12 = 10 : 24

goats : turkeys + ducks = 3 : 5
goats : turkeys + goats + ducks = 3 : 8 = 9 : 24

turkeys : goats : ducks
= 10 : 9 : 24 - 10 - 9
= 10 : 9 : 5

cheers.

[Superbugs]

[quote="ksme"]Pixiedust and Superbug,


Rosyth School 2010 P5 SA2 Maths Paper 2 Q6

Area of triangles ABX + BXY+YDC = 1/2 of Area of rectangle ABCD = 240
Since area of BXZ = 56, the shaded area is 240-56= 184 cm2

I don’t get it. Why Area of triangles ABX + BXY+YDC = 1/2 of Area of rectangle ABCD?

[MathIzzzFun]

Superbugs:

ksme:

Pixiedust and Superbug,


Rosyth School 2010 P5 SA2 Maths Paper 2 Q6

Area of triangles ABX + BXY+YDC = 1/2 of Area of rectangle ABCD = 240
Since area of BXZ = 56, the shaded area is 240-56= 184 cm2

I don't get it. Why Area of triangles ABX + BXY+YDC = 1/2 of Area of rectangle ABCD?

hi

http://i53.tinypic.com/f4qvc5.jpg\">

cheers.