For the past three months grace used her cell phone for 42 minutes,62 minutes and 57 minutes. how many minutes would she have to use her cell phone this month for the average usage over the four months to be 55 minutes this is a math problem

The amount of minutes Grace has to use her cell phone this month is 59 minutes

Step-by-step explanation:

Let

x -----> amount of minutes Grace has to use her cell phone this month

we know that

The average usage during the four months is equal to the sum of the minutes used in the four months divided by four (the number of months)

so

Solve for x

Multiply by 4 both sides to remove the fraction

therefore

The amount of minutes Grace has to use her cell phone this month is 59 minutes

true

step-by-step explanation:

step-by-step explanation:

no, her answer is not correct.   we square the lengths of all sides and then determine whether the pythagorean theorem holds here:

9² + 15² = 306.   this is not equal to the square of the longest side ( that square being 395.   answer c is correct.