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Answers for ---

Question 1

(a) Speed Mr. Chen is driving when he is driving from Town A to B            = ( x 780 km) / (1400 - 0900) (1)

= 450 km / 5 h

= 90 km/h (1)

(b) The Time he reached Town C = [( x 780 km) / 110] h + 1500 (1/2)

                                                = (330 / 110) h + 1500 (1/2)

                                                = 3 h + 1500

                                                = 1800   OR   6 p.m. (1)

(c) Average Speed for the whole journey = 780 km / 9 h

                                                            = 86 km/h

(d) Speed Mr. Chen must travel to get to Town C 2 hours later                   = 330 km / (3 + 2) h

= 330 km / 5 h

= 66 km/h (1/2)

Percentage decrease in speed = []   x 100% (1/2)

                                           = x 100%

                                           = x 100%

                                           = 40% (1)

Question 2

(a) 30 men take 4 hours to fix 2 aeroplanes.

     30 men take 2 hours to fix 1 aeroplane.

     30 men take 6 hours to fix 3 aeroplanes.

     60 men take 3 hours to fix 3 aeroplanes.

     Therefore, no. of more men needed = 60 - 30

                                                        = 30 more men

(b) 5 men take 10 days to paint 1 house.

     5 men take 70 days to paint 7 houses.

     70 men take  5 days to paint 7 houses.

     Therefore, 70 men are required.

Question 3

The interest rate per annum given by Bank A : The interest rate per annum given by Bank B

= (1.8 / 3) : 1

= 0.6 : 1

= 3 : 5

The total amount of money James have in both bank after 2 years

= ( x $15 000) + ( x $5000)

= $15 900 + $5 500

= $21 400

Question 4

(a) Daily rate of his basic salary = $480 / 20 days

                                                 = $24/day

(b) The value of the goods he sold = ($1150 - $480)

                                                  = x $670

                                                  = $2680

(c) Daily rate of his new basic salary = $620 / 20

                                                       = $31/day

(d) The percentage increase of the daily rate of the new basic salary        = x 100%

= x 100%

= 29%

(e) Total amount of money Jack made = ( x $2272) + $620

                                                       = $568 + $620

                                                       = $1188

Question 5

(a) The price difference between paying all at once and buying the computer through the hire purchase system                                               = $(1000 + 184.80 x 9)- $2584

= $2663.20 - $2584

= $79.20 (1)

(b) The interest rate charged on the monthly instalments                           = [$79.20 / ($2584 - $1000)] x 100%  (1)

= ($79.20 / $1584) x 100% 

= 0.05 x 100%

= 5% (1)

Question 6

7 men took 12 hours to make 18 chairs.

7 men took 4 hours to make 6 chairs.

7 men took 28 hours to make 42 chairs. (1/2)

1 man took 196 hours to make 42 chairs.

9 men took 21.78 hours to make 42 chairs. (1 1/2)

Question 7

At first --- 

Pineapple Juice : Mango Juice

           (56 - 8) : 8

                   48 : 8

                    6   : 1          (1/2)

Total Amount = 56 litres

After Mixing and Removing 8 litres of Pineapple Juice ---

Pineapple Juice : Mango Juice

                     6 : 1

Total Amount = 48 litres

Amount of Pineapple Juice = x 48

                                       = 41 litres     (1/2)

Amount of Mango Juice = x 48

                                   = 6 litres      (1/2)

After adding 8 litres of mango juice ---

Amount of mango juice = 6 + 8   

                                 = 14 litres   (1/2)

Therefore,

Amount of Mango Juice : Amount of Pineapple Juice

                            14 : 41

                             :

                             104 : 288

                               13 : 36     (1)