Question

8. You recorded the time in seconds it took for 8 participants to solve a puzzle. The times were: 15.2, 18.8, 19.3, 19.7, 20.2, 21.8, 22.1, 29.4. a. Find the mean b. Find the median c. Write the 5-number summary for this data

Answer 1

Xbar = 20.813

Median = 19.95

5 - number summary :

Minimum = 15.2

Q1 = 19.05; Q2 = 19.95 ; Q3 = 21.95 ; maximum = 29.4

Standard deviation, s = 4.068

Step-by-step explanation:

Given the data:

X : 15.2, 18.8, 19.3, 19.7, 20.2, 21.8, 22.1, 29.4

Ordered data:

15.2, 18.8, 19.3, 19.7, 20.2, 21.8, 22.1, 29.4

The mean (xbar) :

Xbar = Σx / n ; n = sample size = 8

Xbar = 166.8 / 8 = 20.8125

Xbar = 20.813

The median :

1/2 *(n+1)th term

1/2(9) = 4.5

(4 + 5)th term / 2

(19.7 + 20.2) / 2 = 19.95

The five number summary :

Minimum = 15.2

Lower quartile (Q1) = 1/4(9) = 2.25 ; (2nd + 3rd) term / 2

(18.8 + 19.3) / 2 = 19.05

Median (Q2) = 19.95

Upper quartile (Q3) :

3/4(9) = 6.75 = (6th + 7th) / 2

(21.8 + 22.1) / 2 = 21.95

Maximum = 29.4

The standard deviation, s = sqrt[(x - xbar)²/ (n-1)]

Using calculator ;

s = 4.068