Maths Stratergy

1. The world record for throwing a cellphone in 2012 was 102.68 metres. James attempted to beat the record but only managed to throw 97.89m. How much was he short by?

102.68 - 4.79 = 97.89

102.68 - 2.68 = 100.00

100.00 - 2 = 98

98 - .11 = 97.89

2.68 + 2 + .11 = 4.79

2. Sione uploaded a presentation to his blog but it was too big. In the HTML code he saw that the size was 920  pixels wide by  648 pixels high. He thinks if he reduces it to ¾ of the size it is, it should fit. What dimensions does he need to change in the HTML code?

230 pixels wide

920 divided by 4 =

(92 divided by 4 = 4 x 20 = 80  4 x 3 = 12 4 x 20 + 4 x 3 = 92)

4 x 200 = 800

4 x 30 = 120

4 x 200 + 4 x 30 = 920

230 x 4 = 920

162 pixels high

648 divided by 4 =

(64 divided by 4 = 4 x 10 = 40, 4 x 6 = 24, 4 x 10 + 4 x 6 = 64)

4 x 100 = 400

4 x 60 = 240

4 x 100 + 4 x 60 = 640

4 x 2 = 8

640 + 8 = 648

162 x 4 = 648

3. Tiaki is fixing part of his fence. The pickets he needs are .68m long each. How many metres of timber does he need to cut up 45 pickets?

If the timber comes in 5m lengths only what is the minimum amount of lengths he needs to have enough for 45 pickets?

The timber is $3.55/m. How much will he have spent?

Answer: 30.6

Strategy: 0.68 X ? = 45

0.68 X 10 = 6.8

40 = 27.2

0.68 X 5 = 3.4

27.2 + 3.4 = 30.6

4.  Julia is an artist. She has been painting a huge mural for the town centre. For the main colour she used a 20 litre pail of white mixed with a 10 litre pail of blue. Unfortunately she ran out of paint before she finished the mural. She thinks that she will only need 5 more litres in total to finish. How much blue and white paint does she need to mix up to get the 6 litres of paint she needs that is exactly the same colour she has been using?

(1+2 = 3 , It is a ratio problem.)