O-LevelMathematicsNumber4024/21 · Oct/Nov 2022 · Q112 Marks

Abid works in an office for 5 days each week. Each day he works from 08 15 until 1240 and then from 1330 until 1700.

(a)Work out the total time Abid works in one week. Give your answer in hours and minutes.[2]
(b)Abid earns $14.20 per hour. He is given a pay increase of 5%. Calculate the amount Abid earns per hour after the increase.[2]
(c)Each month Abid divides his earnings between rent, bills and savings. He uses 20% of his earnings for rent. He uses 3/8 of his earnings for bills. The rest of his earnings are savings. Find the ratio rent : bills : savings. Give your answer in its simplest form.[3]
(d)Abid invests $2400 in a savings account for 4 years. The account pays simple interest at a rate of r% per year. At the end of 4 years he receives a total of $153.60 in interest. Calculate the value of r.[2]
(e)Abid invests some money in a different savings account. This account pays compound interest at a rate of 1.4% per year. At the end of 5 years there is $1822.38 in the account. Calculate the amount of money Abid invests in this account.[3]

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2022). The mark or mark type is shown in brackets.

[2] (a) 39 [hours] 35 [minutes]; B1 for 2375 [min] or 35 [h] 275 [m] or 7 [h] 55 [m] or 475 [min] or 22 [h] 5 [m] or 17 [h] 30 [m] After 0 scored, SC1 for answer 39 [h] 35 [m] to 39 [h] 36 [m]
[2] (b) 14.91 final answer; M1 for 14.20 + 5/100 × 14.20 oe or B1 for 0.71 seen
[3] (c) 8 : 15 : 17 final answer; M2 for 1/5 k : 3/8 k : 17/40 k soi or 20 : 37.5 : 42.5 oe or for final answer ratio with 8, 15 and 17 in wrong order or M1 for 1/5 k + 3/8 k or 20[%] + 37.5[%] soi
[2] (d) 1.6; M1 for 2400xrx4/100 = 153.60 oe
[3] (e) 1700[.00...]; M2 for 1822.38 / 1.014^5 oe or M1 for x x (1 + 1.4/100)^5 = 1822.38 oe

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