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emmasim [6.3K]
3 years ago
12

2) Working alone, Rob can dig a 10 ft by 10 ft hole in ten hours. Shayna can dig the same hole in seven hours. Find how long it

would take them if they worked together.​
Mathematics
1 answer:
Free_Kalibri [48]3 years ago
8 0

rob can dig 1/10ft in one hour

Shayna can dig 1/7ft in one our

together they can dig

1/10+1/7

(7+10)/70 in one hour

17/70

in for hours they can dig

17/70×4

68/70

the left work is 2/70

in 60 minutes they can dig 17/70

1/70 work can be done in 60 minutes/17

2/70 work can be done in 60/17×2 minutes

7.088 minutes

for the entire work they take 4hours and 7 minutes

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4.) 960 meters in 15 seconds<br> Write the following rate as a unit rate
murzikaleks [220]

Answer:

64

Step-by-step explanation:

960 divided by 15 is 64. The unit rate means one so you are trying to get it to 1 second so just do 15 divided by 15 which is 1, then 960 divided by 15 which is 64

7 0
3 years ago
Bonjour je ne comprend pas cette exercice; si quelqu'un peut m'aider je suis preneuse.
gayaneshka [121]

Answer:

0,24 m

Step-by-step explanation:

La table est un rectanble donc l'angle en  haut à droite est de 90°.

Tu connais donc un angle et le côté opposé à l'angle et tu cherche le côté adjacent.

On sait que tan(â) = \frac{Cote oppose}{Cote adjacent} donc :

tan(40)= \frac{1,27}{x}

\frac{1,27}{tan(40)} = x

donc x ≈ 1,51 m

Le trou du mileu est à \frac{2,54}{2} soit 1,27m du bord.

Donc elle doit taper à 1,51 - 1,27 = 0,24m du trou du milieu.

j'espère avoir été clair.

<h2 />
8 0
2 years ago
A circular garden has a circumference of 113 yards. Lars is digging a straight line along a diameter of the garden at a rate of
natima [27]

Answer:3hrs 59min

Step-by-step explanation:

πd=perimeter

(113÷3.14)

=35.99

9yards=1hr

35.99yards=?

35.99÷9=3hrs 59min

7 0
3 years ago
How many different linear arrangements are there of the letters a, b,c, d, e for which: (a a is last in line? (b a is before d?
inna [77]
A) Since a is last in line, we can disregard a, and concentrate on the remaining letters.
Let's start by drawing out a representation:

_ _ _ _ a

Since the other letters don't matter, then the number of ways simply becomes 4! = 24 ways

b) Since a is before d, we need to account for all of the possible cases.

Case 1: a d _ _ _ 
Case 2: a _ d _ _
Case 3: a _ _ d _
Case 4: a _ _ _ d

Let's start with case 1.
Since there are four different arrangements they can make, we also need to account for the remaining 4 letters.
\text{Case 1: } 4 \cdot 4!

Now, for case 2:
Let's group the three terms together. They can appear in: 3 spaces.
\text{Case 2: } 3 \cdot 4!

Case 3:
Exactly, the same process. Account for how many times this can happen, and multiply by 4!, since there are no specifics for the remaining letters.
\text{Case 3: } 2 \cdot 4!

\text{Case 4: } 1 \cdot 4!

\text{Total arrangements}: 4 \cdot 4! + 3 \cdot 4! + 2 \cdot 4! + 1 \cdot 4! = 240

c) Let's start by dealing with the restrictions.
By visually representing it, then we can see some obvious patterns.

a b c _ _

We know that this isn't the only arrangement that they can make.
From the previous question, we know that they can also sit in these positions:

_ a b c _
_ _ a b c

So, we have three possible arrangements. Now, we can say:
a c b _ _ or c a b _ _
and they are together.

In fact, they can swap in 3! ways. Thus, we need to account for these extra 3! and 2! (since the d and e can swap as well).

\text{Total arrangements: } 3 \cdot 3! \cdot 2! = 36
7 0
3 years ago
Question 11
mamaluj [8]
The first one is the correct answer

Y-7=-3(x+2)
6 0
3 years ago
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