I am assuming the answer could be C
Triangular sequence = n(n + 1)/2
If 630 is a triangular number, then:
n(n + 1)/2 = 630
Then n should be a positive whole number if 630 is a triangular number.
n(n + 1)/2 = 630
n(n + 1) = 2*630
n(n + 1) = 1260
n² + n = 1260
n² + n - 1260 = 0
By trial an error note that 1260 = 35 * 36
n² + n - 1260 = 0
Replace n with 36n - 35n
n² + 36n - 35n - 1260 = 0
n(n + 36) - 35(n + 36) = 0
(n + 36)(n - 35) = 0
n + 36 = 0 or n - 35 = 0
n = 0 - 36, or n = 0 + 35
n = -36, or 35
n can not be negative.
n = 35 is valid.
Since n is a positive whole number, that means 630 is a triangular number.
So the answer is True.
P ( A ) = 0.45 - probability that the land has oil,
P ( B ) = 0.8 - probability that the test predicts it
P ( A ∩ B ) = P ( A ) · P ( B ) = 0.45 · 0.8 = 0.36
Answer: The probability that the land has oil and the test predicts it is 36 %.
Answer:
28 white strands , 20 blue strands and 32 red strands are needed to make a pair of pom-poms
Step-by-step explanation:
Given :A pom-pom manufacturer makes each of its pom-poms with 35% white strands (w), 25% blue strands (b), and 40% red strands (r).
To Find : If each pom-pom has a total of 80 strands, how many of strands of each color are needed to make a pair of pom-poms?
Solution:
Total Strands = 80
White Strands = 35%
No. of white strands = 
Blue Strands = 25%
No. of blue strands = 
Red Strands = 40%
No. of Red strands = 
Hence 28 white strands , 20 blue strands and 32 red strands are needed to make a pair of pom-poms
2 yards = 6 feet
6 times 5 is 30
30 ft squared
