Select the best answer from the choices provided a b c d

C

Step-by-step explanation:

The summation basically means to plug in k=4, 5, 6, 7, 8, and 9 into the formula part   and sum all of them up. So it becomes:

As seen from the work shown, C is the right answer.

54 kilometers per hour

step-by-step explanation:

according to rules:

1 km = 1000 meter

which means that 1 meter = 1/1000 km

1 hour = 3600 second [ as 1 hour = 60 min = 60 *60 seconds ]

which means that 1 second = 1/3600 hour

therefore, 1 kilometer/hour =

thus to convert 15 meter per second to kilometer per hour, we multiply 15 to 3.6 kilometer/hour.

15 meter/second=   which is the required answer.

7/2

(decimal: 3.5)

welcome ; )

step-by-step explanation: