Between which 2 numbers on a number line will √20 be found?

Mathematics

1 answer:

ehidna [41]2 years ago

4 0

Answer:

Since the square root of 20 is around 4.5, we know that ≈4.5 is almost at the half mark between 4 and 5 on the number line.

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The diagram shows the cross-section of a wall of a cinema.

Anna71 [15]

Answer:

280 m²
£133

Step-by-step explanation:

The area of the wall is the sum of the areas of the different sections of the wall. The cost to paint it will be the product of the cost of a tin of paint and the number of tins required.

Here, the shape of the wall can be divided into two trapezoids and a rectangle. Each shape has a corresponding area formula. Left-to-right, their areas are ...

Left Trapezoid

A = 1/2(b1 +b2)h

A = 1/2(10 m +11 m)(4 m) = 42 m²

Middle Rectangle

A = LW

A = (13 m)(11 m) = 143 m²

Right Trapezoid

A = 1/2(b1 +b2)h

A = 1/2(11 m +8 m)(10 m) = 95 m²

Wall Area

The total area to be painted is the sum of the above areas:

total area = 42 m² +143 m² +95 m² = 280 m²

The area that needs to be painted is 280 m².

A tin of paint covers 15 m², so the number of tins needed is ...

(15 m²)t = 280 m²

t = 280/15 = 18 2/3 . . . . . . divide by the coefficient of t

We can only buy whole tins, so we need to buy 19 tins. Their cost will be ...

(£7 /tin)(19 tins) = £133

It will cost £133 to paint the wall.

7 0

2 years ago

Please help!! Write the sum using summation notation, assuming the suggested pattern continues. -9 - 4 + 1 + 6 + ... + 66

fiasKO [112]

$r=-4-(-9)=-4+9=5 \\ \\ a_{1}=-9 \\ \\ a_{n}=66 \\ \\ a_{n}=a_{1}+(n-1)r \\ \\ -9+5(n-1)=66 \\ \\ -9+5n-5=66 \\ \\ 5n-14=66 \\ \\ 5n=80 \\ \\ n=16 \\ \\ S_{n}= \frac{a_{1}+a_{n}}{2} *n \\ \\ S_{n}= \frac{-9+66}{2}*16=57*8=456$