User interface language: English | Español

Date November 2016 Marks available 3 Reference code 16N.2.SL.TZ0.S_5
Level Standard Level Paper Paper 2 Time zone Time zone 0
Command term Find Question number S_5 Adapted from N/A

Question

The weights, W , of newborn babies in Australia are normally distributed with a mean 3.41 kg and standard deviation 0.57 kg. A newborn baby has a low birth weight if it weighs less than w kg.

Given that 5.3% of newborn babies have a low birth weight, find w .

[3]
a.

A newborn baby has a low birth weight.

Find the probability that the baby weighs at least 2.15 kg.

[3]
b.

Markscheme

* This question is from an exam for a previous syllabus, and may contain minor differences in marking or structure.

valid approach     (M1)

eg z = 1.61643 N16/5/MATME/SP2/ENG/TZ0/05.a/M

2.48863

w = 2.49  (kg)      A2     N3

[3 marks]

a.

correct value or expression (seen anywhere)

eg 0.053 P ( X 2.15 ) ,   0.039465      (A1)

evidence of conditional probability     (M1)

eg P ( 2.15 X w P ( X w ) ,   0.039465 0.053

0.744631

0.745     A1     N2

[3 marks]

b.

Examiners report

[N/A]
a.
[N/A]
b.

Syllabus sections

Topic 4—Statistics and probability » SL 4.9—Normal distribution and calculations
Show 181 related questions
Topic 4—Statistics and probability

View options