if n coins are tossed, the probability of x heads is the fraction whose numerator is entry number x of row…

if n coins are tossed, the probability of x heads is the fraction whose numerator is entry number x of row number n in pascals triangle, and whose denominator is the sum of the entries in row number n. the topmost row of the triangle is \row number 0\ and the left - most entry of each row is \entry number 0.\ use the pattern in pascals triangle to find the probability of getting 3 heads when seven fair coins are tossed. the probability of getting 3 heads when seven fair coins are tossed is (type an integer or a simplified fraction.)
Answer
Explanation:
Step1: Identify row and entry
When 7 coins are tossed, we look at row number 7 in Pascal's triangle. We want the entry for 3 heads, so we find the 4th entry (since we start counting from 0) in row 7. In row 7 of Pascal's triangle: 1, 7, 21, 35, 35, 21, 7, 1, the 4th entry is 35.
Step2: Find row sum
The sum of the entries in row 7 of Pascal's triangle is 128 (as shown in the row - sum column).
Step3: Calculate probability
The probability of getting 3 heads when 7 coins are tossed is the ratio of the entry for 3 heads to the sum of the row. So the probability is $\frac{35}{128}$.
Answer:
$\frac{35}{128}$