1ringtone and $3 equals $4, how much is the ringtone

$1

Step-by-step explanation:

Let's call the ringtone r. If the ringtone and $3 equals $4, then we can write the equation $4=$3+r. To solve, all you have to do is isolate the r by subtracting 3 on each side.

I should use at least 304 students

Step-by-step explanation:

Margin error (E) = t × sd/√n

E = 40

sd = 300

confidence level (C) = 98% = 0.98

significance level = 1 - C = 1 - 0.98 = 0.02 = 2%

t-value corresponding to 2% significance level and infinity degree of freedom is 2.326

n = (t×sd/E)^2 = (2.326×300/40)^2 = 17.445^2 = 304 (to the nearest integer)