Anonymous
Anonymous asked in Science & MathematicsMathematics · 1 year ago

# MATH QUESTION?

Find the sum of the statement below

1 + 2 + 3 + 4 + …+ 13 + 14 + 15 + 14 + 13 + …. + 4 + 3 + 2+ 1 =

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• 1 year ago

1+2+3+4 + ... 15 = 120

14+13+12+ . . . 1 = 105

• 1 year ago

Of six cars produced at a particular factory between 8 am and 10 am last Monday morning, test runs revealed three of them to be “lemons.” Nevertheless, three of the six cars were shipped to Dealer A and the other three to Dealer B. Dealer A received all three lemons. What is the probability of this event occurring if, in fact, the three cars shipped to Dealer A were selected at random from the six produced?

• 1 year ago

Split the series into two lines. Pad the last term as a 0 to make it the same number of terms:

. 1 + . 2 + . 3 + . 4 + … + 13 + 14 + 15 +

14 + 13 + 12 + 11 + ... + . 2 + . 1 + . 0

Look at the sum of the terms that are above each other:

. 1 + . 2 + . 3 + . 4 + … + 13 + 14 + 15 +

14 + 13 + 12 + 11 + ... + . 2 + . 1 + . 0

---- .. ---- .. ---- .. ---- .. ... .. ---- .. ---- .. ----

15 + 15 + 15 + 15 + ... + 15 + 15 + 15

So we end up with 15 pairs that each add to 15:

15 × 15 = 225

225

Now you try this:

1 + 2 + 3 + ... + 98 + 99 + 100 + 99 + 98 + ... + 3 + 2 + 1

• geezer
Lv 7
1 year ago

So you start at 1 .. go up to 15 .. and then return to 1

15 is in the middle .. and then you have 15 other 15's

because 14+1=15 ... 13+2=15 .. 12+3=15 .. etc ..etc

So it's 15 + 15 ... Fifteen times

or

15 x 15

225

• 1 year ago

[k=1→n]∑k + [k=1→n-1∑k = [k=1→n]∑n = n²

so 1 + 2 + 3 + 4 + … + 13 + 14 + 15 + 14 + 13 + … + 4 + 3 + 2+ 1 = 15² = 225

• Mike G
Lv 7
1 year ago

Sum of the sequence 1 to 14 = 7(2+13) = 105

Total = 15+210 = 225

• ted s
Lv 7
1 year ago

15 x 15 = 225

• ?
Lv 7
1 year ago

Is there some reason you couldn't just use a calculator to figure this out?

1 + 2 + 3 + 4 + …+ 13 + 14 + 15 + 14 + 13 + …. + 4 + 3 + 2+ 1 =

2 [1+2+3+4+5+6+7+8+9+10+11+12+13+14] + 15 =

2 [105]+15 =

225.....................ANS

• 1 year ago

(1 + 2 + 3 + 4 + …+ 13 + 14) + 15 + (14 + 13 + …. + 4 + 3 + 2+ 1)

= 105 + 15 + 105

= 225