Q&A - P3 Math

[MathIzzzFun]

peapot:

Hi, can help me with this P3 question?


Father is 5 times as old as Calvin now. In 10 years' time, their total age will be 74 years old. How old is Calvin now?

I m always confused with these \"age\" problem sum.

Another \"age\" question. Mr Tan is 42 years old and his son is 8 years old now. In how many years time will Mr Tan be twice as old as his son?

Pls enlighten me. Thanks!!

Hi

Q1.Father is 5 times as old as Calvin now. In 10 years' time, their total age will be 74 years old. How old is Calvin now?

In 10 years' time, both will be older by 10 years, ie total age will increase by 10 + 10 = 20. So, total age now = 74 - 20 = 54
Calvin's age now = 54/6 = 9

Q2. Mr Tan is 42 years old and his son is 8 years old now. In how many years time will Mr Tan be twice as old as his son?

The age difference will remain the same.

Age difference = 42 - 8 = 34

When Mr Tan is twice as old as his son, and since the age difference is 34, Mr Tan will be 2 x 34 = 68
68 - 42 = 26 --> Mr Tan will be twice his son's age in 26 years' time.

cheers.

[ttlkbs]

Now

Calvin => 1 unit
Father => 5 units
10 years time
Calvin => 1 unit + 10
Father => 5 units + 10

Calvin’s age + Father’s age = 74
6 units + 20 = 74
6 units = 54
1 unit = 9

Calvin is 9 yrs old now.

[chowon]

peapot:

Hi, can help me with this P3 question?


Father is 5 times as old as Calvin now. In 10 years' time, their total age will be 74 years old. How old is Calvin now?

I m always confused with these \"age\" problem sum.

Another \"age\" question. Mr Tan is 42 years old and his son is 8 years old now. In how many years time will Mr Tan be twice as old as his son?

Pls enlighten me. Thanks!!

I found that drawing out the model really helpful in solving problems relating to age. Give it a try.

[fohope]

Hi,

Pls help to solve the problem sum. Thank in advance.

A group of classmates plan to buy a present for their teacher. If each of them pay sgd2.00, they will be short of sgd3.00 for the present.
If each of them pay sgd3.00,they will have an extra of sgd3.00. If there are fewer than 10 classmates, how much does the present cost ?

[buds]

Sharon is thinking of a number between 300 and 400. When she divides it by 6 or 8, it leaves a remainder of 5. What *number is she thinking of?


*There’s more than one possible answer…

[smartmummy]

fohope:

Hi,

Pls help to solve the problem sum. Thank in advance.

A group of classmates plan to buy a present for their teacher. If each of them pay sgd2.00, they will be short of sgd3.00 for the present.
If each of them pay sgd3.00,they will have an extra of sgd3.00. If there are fewer than 10 classmates, how much does the present cost ?

Time table 2: 2 4 6 8 10 12 14 16 18
+3: 5 7 9 11 13 15 17 19 21
Time table 3:3 6 9 12 15 18 21 24 27
-3 : 0 3 6 9 12 15
Price is sgd 9

[tianzhu]

smartmummy:

fohope:

Hi,

Pls help to solve the problem sum. Thank in advance.

A group of classmates plan to buy a present for their teacher. If each of them pay sgd2.00, they will be short of sgd3.00 for the present.
If each of them pay sgd3.00,they will have an extra of sgd3.00. If there are fewer than 10 classmates, how much does the present cost ?

Time table 2: 2 4 6 8 10 12 14 16 18
+3: 5 7 9 11 13 15 17 19 21
Time table 3:3 6 9 12 15 18 21 24 27
-3 : 0 3 6 9 12 15
Price is sgd 9

Hi

Making a table or Listing is a suitable method for this question as the numbers are small.

Do take note that the number of classmates remains the same in both tables.

The number of classmates is 6 and the price of present is 15.

Alternate ways are MD or using Gap and Difference.

3+3 ------ 6

Difference ------- 3-2 ------- 1

Number of classmates -------- 6/1

Present’s cost --------- (6*2) + 3 ------ 15

Best wishes

[tianzhu]

buds:

Sharon is thinking of a number between 300 and 400. When she divides it by 6 or 8, it leaves a remainder of 5. What *number is she thinking of?


*There's more than one possible answer...

Hi buds

You’re correct.

There are 4 possible answers.

Best wishes

[MathIzzzFun]

fohope:

Hi,

Pls help to solve the problem sum. Thank in advance.

A group of classmates plan to buy a present for their teacher. If each of them pay sgd2.00, they will be short of sgd3.00 for the present.
If each of them pay sgd3.00,they will have an extra of sgd3.00. If there are fewer than 10 classmates, how much does the present cost ?

Hi

http://i45.tinypic.com/vimhyd.png\">

and using \"make a list\" heuristics ...

http://i48.tinypic.com/fyzloz.png\">

cheers.

[fohope]

tianzhu:

smartmummy:

[quote=\"fohope\"]Hi,

Pls help to solve the problem sum. Thank in advance.

A group of classmates plan to buy a present for their teacher. If each of them pay sgd2.00, they will be short of sgd3.00 for the present.
If each of them pay sgd3.00,they will have an extra of sgd3.00. If there are fewer than 10 classmates, how much does the present cost ?

Time table 2: 2 4 6 8 10 12 14 16 18
+3: 5 7 9 11 13 15 17 19 21
Time table 3:3 6 9 12 15 18 21 24 27
-3 : 0 3 6 9 12 15
Price is sgd 9

Hi

Making a table or Listing is a suitable method for this question as the numbers are small.

Do take note that the number of classmates remains the same in both tables.

The number of classmates is 6 and the price of present is 15.

Alternate ways are MD or using Gap and Difference.

3+3 ------ 6

Difference ------- 3-2 ------- 1

Number of classmates -------- 6/1

Present’s cost --------- (6*2) + 3 ------ 15

Best wishes[/quote]Thanks Tianzhu,SmartMummy and MathIzzzfun for your reply.

Hi Tianzhu,
Could you show me the table method?