Select the best answer for the question.

Isaac downloaded 7 ringtones. Each polyphonic ringtone costs $3.25, and each standard ringtone costs $1.50. If he spends a total

anzhelika [568]

Answer:

$6\ polyphonic\ ringtones$ and $1\ standard\ ringtone$

Step-by-step explanation:

Let

x -----> the number of polyphonic ringtones

y ----> the number of standard ringtones

we know that

$x+y=7$

$x=7-y$ -----> equation A

$3.25x+1.50y=21$ -----> equation B

Solve the system of equations by substitution

Substitute equation A in equation B and solve for y

$3.25(7-y)+1.50y=21$

$22.75-3.25y+1.50y=21$

$3.25y-1.50y=22.75-21$

$1.75y=1.75$

$y=1\ standard\ ringtones$

Find the value of x

$x=7-1=6\ polyphonic\ ringtones$

6 0

2 years ago

Read 2 more answers

If you inflate a beach ball with 14,130 cubic inches of air, what will its radius be? Use 3.14 for π. Round to the nearest whole

GREYUIT [131]

Answer: 15

Step-by-step explanation:

The answer is because if you divide 14,130 by 3.14. You'll get 4500 and then divide that by 300 and your finally is 15

8 0

2 years ago

Lengths of full-term babies in the US are Normally distributed with a mean length of 20.5 inches and a standard deviation of 0.9

mash [69]

Answer:

66.48% of full-term babies are between 19 and 21 inches long at birth

Step-by-step explanation:

Normal Probability Distribution:

Problems of normal distributions can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the z-score of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.

Mean length of 20.5 inches and a standard deviation of 0.90 inches.

This means that $\mu = 20.5, \sigma = 0.9$