The Association of Business Executives Certificate

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17 IQM0608

112 –

100

12

(b) (i)

•

P (X > 112) = P Z <

=

= 1.5

= 0.0668

8

8

90 – 100

–10

•

P (X < 90) = P Z <

=

= –1.25 = 0.1056

8

8

•

P (80 ≤ X ≤ 90) = P

90 – 100

80

– 100

–10

–20

^Z

<

– P

Z <

=

–

8

8

8

8

= -1.25 – –2.5

= 0.1056 – 0.00621

= 0.09939

(ii)

= 100 × 0.1056

= 10.56

= 11 chocolate bars

Q6 (a)

Weekly sales (number

Mid-point

Frequency

of books)

X

f

210 to 219

214·5

7

220 to 229

224·5

10

230 to 239

234·5

12

240 to 249

244·5

7

250 to 259

254·5

4

40

2. 
   (i)
   

Weekly book sales by a bookshop over 40 week period

14
12

10

y

• 
  ₈
  

n e u q
e
r ⁶
F

4
2
0

210 220 230 233 240 250 260

Weekly sales (number)

The histogram is slightly (positively) skewed.

2. 
   The mode is approximately 233 books.
   

IQM0608 18

(c)
		Weekly sales	Mid-point	Frequency