Asap for brainliest: the time required to finish a test is normally distributed with a mean of 60 minutes and a standard deviation of 10 minutes. what is the probability that a student will finish the test between 40 and 70 minutes?

0.81859

Step-by-step explanation:

Using the formula ;

Z =

where u = mean

Therefore the probability that a student will finish the test between 40 and 70 will be :

P ( 40≤X≤70 ) = P(X≤70) - P(X≤40)

P ( 60-40/10) , P( 60 - 70 / 10)

=  2 , -1

= P (Z ≤ 2) - P( Z ≤ -1 )

From normal table , we have

0.97725 - 0.15866

Therefore the probability that a student will finish the test between 40 and 70 minutes = 0.81859

rick has $1400 and sally has $1500

step-by-step explanation:

to find amount of money rick has after 10 years :

principal = $1000 , time = 10 years , rate = 4% annually

to find amount of money sally has after 10 years :

her friend gives to pay her $50 per year, therefore money she has after 10 years = 50 × 10 = $500

also, sally gets $1000 after 10 years,

therefore, total amount of money sally has after 10 years = 500 + 1000 = $1500

so, after 10 years : rick has $1400 and sally has $1500

x =-.20752

step-by-step explanation:

4^(x+2)=12

4^(x+2)=12

take the log base 4 on each side

log 4 (4^(x+2) = log 4(12)

we know log b(a^y) = y log b (a)

(x+2) log 4(4) = log 4 (12)

x+2 = log 4 (12)

we know   logb c = loga c/loga b

we want to convert to base 10   so a = 10

by default, we do not write the 10   c = 4   and b = 10

log4 10 = log 12/log 4

log4 10 = log 12/ log 4

x+2 = log 12/ log 4

subtract 2 from each side

x +2 -2 = log 12/ log 4 -2

x = 1.79248125 -2

x =-.20752