Day care centers expose children to a wider variety of germs than the children would be exposed to if they stayed at home more often. this has the obvious downside of more frequent colds and other illnesses, but it also serves to challenge the immune system of children at a critical stage in their development. a study by gilham et al. (2005) tested whether social activity outside the house in young children affected their probabilty of later developing the white blood cell disease acute lymphoblastic leukemia (all), the most common cancer of children. they compared 1272 children with acute lymphoblastic leukemia to 6238 children without acute lymphoblastic leukemia. of the acute lymphoblastic leukemia kids, 1020 had significant social activity outside the home (including day care) when younger. of the kids without acute lymphoblastic leukemia, 5343 had significant social activity outside the home. the rest of the children in both groups lacked regular contact with children who were not in their immediate surroundings.

a.) is this an experimental or observational study?

b.) what are the proportions of children with significant social activity in children with and without acute lymphoblastic leukemia?

c.) what is the odds ratio for acute lymphoblastic leukemia, comparing the groups with and without significant social activity?

d.) what is the 95% confidence interval for this odds ratio?

e.) does this confidence interval indicate that the amount of social activity is associated with acute lymphoblastic leukemia? if so, did the children with more social activity have a higher or lower occurence of acute lymphoblastic leukemia?

f.) the researchers interpreted their study results in terms of the differing immune system exposure of the children, but gave several alternative explanations for the pattern. can you think of any possible cofounding variables?

x=12 units bd= 10 units

step-by-step explanation:

solution:

the given function is ,

      =

the three roots of this quadratic function is , 0 ,8 and 10.all the roots are real and rational.

if a quadratic equation is of the form ,

sum of the roots = a + b +c= 0+8+10=18=  

product of roots taken two at a time = a b + b c+ c a = 0+80+0=80 =  

product of roots = a b c = 0=  

there are 11 doors in a hall starting from 0 to 11.the entry in the hall is permitted through gate number 0 and exit is allowed through only gate number 8 and 10.so, three roots(0,8,10) of quadratic function is given by entry and exit route of this hall.

2 & 7

step-by-step explanation:

he climbs 300 ft/hr at a constant rate. the peak is at 1,500 ft.

when going up, he reaches 600 ft in 2 hours. remember, that he is going in a constant rate. divide 600 with 300:

600/300 = 2

assuming that he takes the same route back (meaning that it's a 1500 ft route back, you can solve.

note also that you are solving when he gets back to 600 ft after he reaches the peak.

first, find the amount of hours it takes to get up the peak. divide the total amount (1500), with the ft/her (300) to get the amount of hours (x):

1500/300 = x

x = 5

it takes jamie 5 hours to get up. now, he is returning down, and reaches 600 (his current destination). remember that he climbs at a constant 300 ft/hr. divide 600 with 300:

600/300 = x

x = 2

now add the two numbers together.

x = 5 + 2 = 7

jamie takes 7 hours to go up the mountain and reach his current position when descending.

(total amount/constant rate) = (time).

remember that it is a constant rate, so in total, when he gets back down the mountain, it will take the same amount of time as when he goes up. the total amount for the round trip is: 5 + 5 = 10.

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c. 27 units.

step-by-step explanation:

we are told that in circle a, ∠bae ≅ ∠dae.

we can see from our given diagram that in and ;

, as these are radii of our given circle.

therefore, by sas congruence postulate.

hence, side be will be equal to side de as corresponding parts of congruent triangles are congruent. so we can set an equation to find the value of x as:

now let us substitute x=17 in the expression for the length of be.

therefore, length of be will be 27 units and option c is the correct choice.