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Kryger [21]
2 years ago
11

Working alone, Elisa can sweep a porch in 11 minutes. Pranav can sweep the same porch in 13 minutes. How long would it take if t

hey worked together.
A. 5.96 Minutes
B. 5.86 Minutes
C. 5.21 Minutes
D. 4.87 Minutes
Mathematics
1 answer:
GaryK [48]2 years ago
5 0

Elisa, e = 11mins

Prenav,p = 13mins

time to complete, t

1 = t( 1/11 + 1/13) = t (24/143)

t = 143/24 = 5.96min

Answer is A 5.96mins

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In a group of 90 students, 65 watch rugby, 71 play a sport and 15 do neither.
Dimas [21]

Answer:

\frac{14}{75} probability of selecting a student who plays a sport but does not watch rugby out of the people who play a sport.

Step-by-step explanation:

"Find the probability that a student chosen at random from those who play a sport  does not watch rugby."

90-15= 75 students either play a sport OR watch rugby

65+71-75=

136-75=

61 people play a sport AND watches rugby

14 people play a sport and DOES NOT watch rugby

\frac{14}{75} is the probability of selecting a student who plays a sport but does not watch rugby out of the people who play a sport.

4 0
1 year ago
The radius of a right circular cone is increasing at a rate of 1.4 in/s while its height is decreasing at a rate of 2.1 in/s. At
kow [346]

Given:

\dfrac{dr}{dt}=1.4\text{ in/s}

\dfrac{dh}{dt}=-2.1\text{ in/s}

To find:

The rate of change in volume at r=120\text{ in. and }175\text{ in.}

Solution:

We know that, volume of a cone is

V=\dfrac{1}{3}\pi r^2h

Differentiate with respect to t.

\dfrac{dV}{dt}=\dfrac{1}{3}\pi\times \left[(r^2\dfrac{dh}{dt}) + h(2r\dfrac{dr}{dt})\right]

Substitute the given values.

\dfrac{dV}{dt}=\dfrac{1}{3}\times \dfrac{22}{7}\times \left[(120)^2(-2.1) +175(2)(120)(1.4)\right]

\dfrac{dV}{dt}=\dfrac{22}{21}\times \left[-30240+58800\right]

\dfrac{dV}{dt}=\dfrac{22}{21}\times 28560

\dfrac{dV}{dt}=29920

Therefore, the volume of decreased by 29920 cubic inches per second.

6 0
2 years ago
Write a multiplication fact that goes with this division fact. 24 ÷ 4 = 6
Mekhanik [1.2K]
Well I wild have to say 6x4=24
3 0
2 years ago
Read 2 more answers
Alice has a 4-inch by 5-inch photo of your school’s championship girls’ ice hockey team. To celebrate their recent
Pachacha [2.7K]

Alice should pick the enlarged-photo with dimensions of 8-inch by 10-inch.

Step-by-step explanation:

Step 1:

In order for a part of the photo to not be cut off, the enlarged photo's dimensions should be of a constant ratio with the original photo's dimensions.

We divide the dimensions of the enlarged-photo with the dimensions of the original photo to check which has a constant ratio.

Step 2:

The original photo was a 4-inch by 5-inch photo.

Option 1 is 7-inch by 9-inch, so the ratios are

\frac{7}{4} = 1.75, \frac{9}{5} = 1.8. The ratios are different so this cannot be the enlarged photo's dimensions.

Option 2 is 8-inch by 10-inch, so the ratios are

\frac{8}{4} = 2, \frac{10}{5} = 2. The ratios are the same so this can be the enlarged photo's dimensions.

Option 3 is 12-inch by 16-inch, so the ratios are

\frac{12}{4} = 3, \frac{16}{5} = 3.2. The ratios are different so this cannot be the enlarged photo's dimensions.

So the enlarged-photo with dimensions of 8-inch by 10-inch should be picked.

7 0
2 years ago
A length is measured as 21cm correct to 2 significant figures. what is the upper bound for the length?​
Leno4ka [110]

the upper bound for the length is  21.5  cm .

<u>Step-by-step explanation:</u>

Lower and Upper Bounds

  • The lower bound is the smallest value that will round up to the approximate value.
  • The upper bound is the smallest value that will round up to the next approximate value.

Ex:- a mass of 70 kg, rounded to the nearest 10 kg, The upper bound is 75 kg, because 75 kg is the smallest mass that would round up to 80kg.

Here , A length is measured as 21cm correct to 2 significant figures. We need to find what is the upper bound for the length . let's find out:

As discussed above , upper bound for any number will be the smallest value in decimals which will round up to next integer value . So , for 21 :

⇒ 21.5  cm

21.5 cm on rounding off will give 22 cm . So , the upper bound for the length is  21.5  cm .

7 0
2 years ago
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