David ran on a straight track. Every time he ran 480 m, he took a break. After 2 breaks, he still had to run 120 m to complete the track. If the track was twice as long as the playground, what is the distance of the playground?

540m

Step-by-step explanation:

The distance of the track is is equal to the playground's distance.

-The total distance covered is obtained by summing 120 and the distance per break by the total number of breaks:

-The distance of the playground half the track's distance:

Hence, the distance of the playground is 540m

a. the residual plot for model 1 has a random pattern and is a good fit for the data.

solution:

→c= a b , that is product of a and b is possible only when when a is m × n matrix and b is n × p matrix.

that is, number of columns of a= number of rows of b.

so, size of matrix , c= a b is , if a = (m × n)matrix

b= (n × p)matrix

then a b = [ (m × n)matrix] ×[   (n × p)matrix ]

→→c= a b= [m × p ] matrix

→→size of product a b will be equal to = number of rows of a × number of columns of b