Least to greatest -4.3, -82.5, -41 4/5, -13 1/8

Jack is 27 years older than Susan. In 5 years he will be 4 times as old as she is. Find the present ages of jack and Susan

riadik2000 [5.3K]

X - Jack's age
y - Susan's age

Jack is 27 years older than Susan.
$x=y+27$

In 5 years he will be 4 times as old as she is.
$x+5=4(y+5)$

The system of equations:
$x=y+27 \\ x+5=4(y+5) \\ \\ \hbox{substitute y+27 for x in the 2nd equation:} \\ y+27+5=4(y+5) \\ y+32=4y+20 \\ y-4y=20-32 \\ -3y=-12 \\ y=\frac{-12}{-3} \\ y=4 \\ \\ x=y+27=4+27=31$

Jack is 31 years old and Susan is 4 years old.

5 0

2 years ago

Use Lagrange multipliers to find three positive numbers whose sum is 210 and whose product is maximum. (Enter your answers as a

nalin [4]

Answer: the three positive numbers are; 70, 70, 70

Step-by-step explanation:

Given that sum is equal = 210

Lets ( x, y, z ) be the three positive numbers

such that

x + y + z = 210

what is the maximum of xyz

take f(x,y,z) = xyz

Q(x,y,z) = 0

x + y + z -210 = 0

consider the function

F(x,y,z) = f(x,y,z) + λQ(x,y,z)

F = xyz + λ(x+y+z-210)

dF/dx = 0 ⇒ yz + λ(1) = 0 ⇒ λ = -yz ..............equ(1)

dF/dy = 0 ⇒ xz + λ(1) = 0 ⇒ λ = -xz.................equ(2)

dF/dz = 0 ⇒ xy + λ(1) = 0 ⇒ λ = -xy...............equ(3)

Now

equ(1)/equ(2) ⇒ λ/λ = -yz/-xz ⇒ x = +y

equ(1)/equ(3) ⇒ λ/λ = - yz/-xy ⇒ x = +z

⇒ y = z = x

by substitution

x + y + z = 210

x + x + x = 210

3x = 210

x = 210/3 = 70

∴ x, y, z = 70, 70 ,70

MAXIMUM

∛xyz = 70 { when x = y = z = 70}

7 0

2 years ago

A phone company charges $0.45 for the first minute and $0.35 for each additional minute for a long distance call. Which numerica

Vinvika [58]

0.45+19(0.35)

Total cost $7.10 (0.45+6.65)

8 0

2 years ago

Read 2 more answers

Ken and Hamid run around a track. It takes Ken 80 seconds to complete a lap. It takes Hamid 60 seconds to complete a lap. Ken an

likoan [24]

The <em><u>correct answer</u></em> is:

Ken will have run 3 laps and Hamid will have run 4.

Explanation:

To find this, we first find the number of seconds that will have passed when they meet again. We use the LCM, or least common multiple, for this. First we find the prime factorization of each number:

80 = 10(8)

10 = 5(2)

8 = 2(4)

4 = 2(2)

80 = 2(2)(2)(5)(2)

60 = 10(6)

10 = 5(2)

6 = 2(3)

60 = 2(2)(3)(5)

For the LCM, we multiply the common factors by the uncommon. Between the two numbers, the common factors are 2, 2 and 5. This makes the uncommon 2, 2, and 3, and makes our LCM

2(2)(5)(2)(2)(3) = 240

This means every 240 seconds they will both be at the start line.

Since Ken completes a lap in 80 seconds, he completes 240/80 = 3 laps in 240 seconds.

Since Hamid completes a lap in 60 seconds, he completes 240/60 = 4 laps in 240 seconds.

7 0

2 years ago

Read 2 more answers

You offer senior citizens a 20% discount on their tune-ups at your gas station. Assuming that an average of 50 senior citizens g

andreyandreev [35.5K]

Percentage of discount given to senior citizens for tune-ups at the gas station = 20%
Average number of senior citizens visiting the gas station per month = 50
Average price of tune-up before discount = $49.95
Total amount that would
have been collected before discount = 49.95 * 50
= 2497.50 dollars
Total amount of discount given = (20/100) * 2497.50
= 499.50 dollars
I hope that the procedure is clear enough for you to understand.

6 0

2 years ago