I NEED HELP QUICKLY!!! What is the sum of the first 140 positive multiples of 3?
1 answer:
Answer:
C
Step-by-step explanation:
The multiples of 3 are
3, 6, 9, 12, 15, ...........
The terms form an arithmetic sequence with common difference of 3.
The sum to n terms is
=
[2a₁ + (n - 1)d ]
where a₁ is the first term and d the common difference
Here a₁ = 3 and d = 3, thus
=
[ (2 × 3) + (139 × 3) ]
= 70(6 + 417) ] = 70 × 423 = 29610 → C
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Answer:
Total area to be painted in gold = 24000 cm²
Step-by-step explanation:
Total height of the stairs = 120 cm
Total standing stairs = 4
Therefore, height or width of one standing stair as shown in the picture,
=
= 30 cm
Length of every stair has = 100 cm
Every horizontal and vertical stair has the same area.
Area of one stair = Length × Width
= 100 × 30
= 3000 cm square
There are 4 horizontal and 4 vertical similar stairs to be painted in gold.
Total area to be painted in gold = 8 × Area of one stair
= 8 × (3000)
= 24000 cm²
Total area to be painted in gold = 24000 cm²
