Question

In a survey, 32 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $49 and standard deviation of $18. Construct a confidence interval at a 98% confidence level.

Give your answers to one decimal place.

±

Answer 1

Solution :-

Given :-

Mean = 49

Sample Size ( n ) = 32

Std Deviation ( s ) = 18

At 98 % CI level ' t ' is ,

= 1 - 98 %

= 1 - 0.98

= 0.02

/2 = 0.01

t /2 , df = 2.453.

At 98 % CI for Mean is

49   2.453 * ( 18 / 32 )

49 7.805

( 41.2 , 56.8 )

At 98 % Confidence Interval for mean is ( 41.2 , 56.8 )