Q&A - PSLE Math

[tianzhu]

htn:

Hi, please help

A pair of hamsters can produce a pair of baby hamsters every month. The baby hamsters take a month before they can reproduce another pair of baby hamsters.
How many pairs of hamsters (adult and baby) will there be by the end of 6 months??
TIA

Hi

I believe we have a question similar to yours in one of our earlier posts.

I think this is a Maths Olympiad type question and is about Fibonacci Sequence.

To begin, please follow this link to find out more about FS.
http://plus.maths.org/content/os/issue3/fibonacci/index

For P6 students, this question should come under the topic of “Number Patterns”

The sequence is as follow:
1,1,2,3,5,8,13,21,23,34,55,89 …………

Now try to understand the number sequence and look for a pattern, one will see that the next number is obtained by adding the two numbers before it.

For example,
1+1=2
1+2=3
2+3=5

Your question asks for the number at the end of 6 months, so the list is not too long, still manageable if PSLE kids choose to use “Systematic Listing”. Alternative way such as “tree” or “branching” method could also come in handy.

Hope this helps.

[Cheerfuldad]

Hi all,


Please help.

Q1. Varsha had some 20-cent and 50 cent coins. 7/8 of the coins were 20 cent coins and the rest were 50 cent coins. After Varsha had spent $72.50 worth of 50 cent coins and 5/7 of the 20 cent coins, she had 2/7 of the coins left. Find the total amount of money Varsha left.

Q2. The ratio of the no of beads John had to the no of beads Sally had was 3:7 at first. After Sally had given some beads to John, Sally had 76 beads less than John. The ratio of john’s number of beads to Sally’s number of beads became 3:2.
a). How many beads did Sally give to John?
b). What percentage of her beads did Sally give to John?

Q3. Mary and Ben took 49 hrs to complete their Science project. They worked separately on their own project. If Mary had worked 5 hrs less and Ben had worked 6 hrs more, Mary would have put in 2 hrs more than Ben. How many hrs did Mary put in for the Science project?

TIA

[Suz855]

Q3. Mary and Ben took 49 hrs to complete their Science project. They worked separately on their own project. If Mary had worked 5 hrs less and Ben had worked 6 hrs more, Mary would have put in 2 hrs more than Ben. How many hrs did Mary put in for the Science project?


My propose work solution,

[][][][]Mary\tBen
Before 1u + 7\t1u-6\t
Change -5h\t+6h
after 1u+2\t1u

1u+7 + 1u – 6 = 49
2u = 48
1u = 24

Mary\t31h
Ben\t18h

Check\t\t
(Mary)31-5 = 26
(Ben)18+6 = 24

[Vtsy]

http://i55.tinypic.com/dpxow6.jpg\">

[Vtsy]

I am sorry that the picture is tilted. I really need help in solving this question as I can’t seem to find the formula to it.


Thank you for the help.

[JonC]

4th = 32


12th = 192

15th = 285


6th = 60
7th = 77
8th = 96
9th = 117
10th = 140
13th = 221
14th = 252

Go figure out, don’t be lazy

For your info, there is this Picture Editor which and rotate the picture to portrait.

[tianzhu]

KRR:

Hi all,

I need help with this question.

On Saturday pants in a shop were sold at $30 each.
On Sunday the price of pants was reduced and number of pants sold
increased by 50% while the amount collected increased by 25%.

Find the price of pair of pants sold on Sunday.

Thanks in advance.
KRR

Hi KRR

Good Morning.

This is an interesting question. At first glance, it has too many unknowns for one to solve it. It should keep PSLE kids’ backsides glued to the chairs for some time.

You may use MD or “Number*Value”.

Due to time constraints, I shall only offer some draft this time by giving you the steps for MD.

Draw 2 boxes to show the number of pants sold on Saturday.
To use the box to show values, draw each box 30 times bigger. (30 units)
Amount collected on Saturday -------- 2*30 -------60units

Draw 3 boxes to show the number of pants sold on Sunday. (50% increase)
Amount collected on Saturday -------- 75 units (25% increase)

Price of pair of pants sold on Sunday ------- 75/3 -------25

Hope this helps.

Best wishes

[tianzhu]

Cheerfuldad:

Q2. The ratio of the no of beads John had to the no of beads Sally had was 3:7 at first. After Sally had given some beads to John, Sally had 76 beads less than John. The ratio of john's number of beads to Sally's number of beads became 3:2.
a). How many beads did Sally give to John?
b). What percentage of her beads did Sally give to John?

Hi

A student should take note the total number of beads remains the same in the before and after scenarios.

You may work with MD or UM (Units Method).

Before
John:Sally ------ 3:7

After
John:Sally ------ 3:2 -------6:4 (Use equivalent ratios, make the total number of units the same)

2 units ------- 76
1 unit ------ 38

a) Sally gave 3 units or 3*38 (114) to John

b) 3/7*100% ------42.86%

Hope this helps.

Best wishes

[MathIzzzFun]

Cheerfuldad:

Hi all,


Please help.

Q1. Varsha had some 20-cent and 50 cent coins. 7/8 of the coins were 20 cent coins and the rest were 50 cent coins. After Varsha had spent $72.50 worth of 50 cent coins and 5/7 of the 20 cent coins, she had 2/7 of the coins left. Find the total amount of money Varsha left.

TIA

Hi

hope this helps ..

http://i51.tinypic.com/v74420.jpg\">

cheers.

[Vtsy]

Hi,


I do know the answers to the pattern by counting. I’m looking for the working to getting that or rather, the formula to find the nth term. Please advice. Thanks