Currently, the standard deviation is 10, because on average the cards were $10 away from the mean.
Adding another card with value $25 would decrease the standard deviation because it is closer to the mean the the current standard deviation.
Answer:
You can make 64 different sums (which includes a sum of $0 using none of the coins).
Step-by-step explanation:
The number of sums you can make is equal to:
⁶C₀ + ⁶C₁ + ⁶C₂ + ⁶C₃ + ⁶C₄ + ⁶C₅ +⁶C₆ = 1 + 6 + 15 + 20 + 15 + 6 + 1 = 64
